Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Geoffrey Garen]

OK.

Geooff

> On Jun 24, 2020, at 12:19 PM, Saam Barati  wrote:
> 
> If we're only doing this for JSC, I don't think we need this, as none of us 
> care.
> 
> If we want to do it for all of WK testing, we should include this for folks 
> who care about having O0-style stack traces.
> 
> - Saam
> 
>> On Jun 24, 2020, at 12:17 PM, Geoffrey Garen > > wrote:
>> 
>> Is "-fno-inline -fno-optimize-sibling-calls” still on the table?
>> 
>> Thanks,
>> Geoff
>> 
>>> On Jun 24, 2020, at 10:28 AM, Mark Lam >> > wrote:
>>> 
>>> I forgot to add ...
>>> 
 On Jun 24, 2020, at 10:26 AM, Mark Lam >>> > wrote:
 
 Based on all the feedback given so far, it looks like we can move forward 
 with the following plan:
 1. JSC Debug test bots will build their own local jsc with O3 before 
 running the tests.
>>> 
>>> 1.5 JSC EWS bot will also run with an O3 Debug build.
>>> 
>>> Mark
>>> 
 2. The rest of the build and test bots will remain unchanged.
 
 Let's move forward with this and get the Debug JSC test bot functional 
 again.
 
 Thanks.
 
 Mark
 
 
> On Jun 19, 2020, at 2:58 PM, Alexey Proskuryakov  > wrote:
> 
> 
> 
>> 19 июня 2020 г., в 1:11 PM, Mark Lam > > написал(а):
>> 
>> 
>> 
>>> On Jun 19, 2020, at 10:24 AM, Geoffrey Garen >> > wrote:
>>> 
> On Jun 19, 2020, at 8:04 AM, Geoffrey Garen  > wrote:
> 
> Can you explain more about what "O3 with no-inlining” is? How does 
> --force-opt=O3 avoid inlining? Would this fully resolve Simon concern 
> about stack traces, or would something still be different about stack 
> traces?
 There doesn't exist a way to do this now, but it'd be trivial to add a 
 way. I won't claim it fixes all stack traces differences, but I'd 
 think compiling using "-fno-inline -fno-optimize-sibling-calls" would 
 get us pretty far in crashing stack traces being similar enough.
>>> 
>>> Sounds good.
>>> 
>>> I think we should try to refine the proposal along these lines, to 
>>> minimize the downsides. I won’t speak for Simon, but for me, being able 
>>> to ensure a clear backtrace from a bot would be a big improvement.
>>> 
> And again, I think this discussion would get a lot more focused if 
> the change could apply only to JSC code, and not also to WTF code.
 I believe Mark's proposal, initially, is just to make JSC do this. So 
 I don't see the point of compiling WTF differently. JSC can kick off 
 its own build, and run Debug+O3 tests faster than it can run Debug+O0 
 tests. Given people working on JSC want this, and people working on 
 JSC defend these tests, and that these test results are more stable 
 (see below), we should make this change for JSC.
 
 I was trying to convince folks defending non-JSC testing, that they 
 too, should want this. I'm not going to pull teeth here. If folks want 
 their tests to take ~10x longer to run, they're entitled to make that 
 tradeoff.
>>> 
>>> Got it.
>> 
>> I'm of the same mind as Saam.  We want this change for the JSC bots, and 
>> from the time measurements I’ve collected, we can afford to do a clean 
>> build for the JSC Debug test runs using O3, and still come out way ahead.
> 
> This seems like a reasonable plan. You didn't mention what hardware you 
> measured with, but it seems certain to be beneficial on any current 
> hardware.
> 
> I need to mention that we saw unexplained and very large impact on JSC 
> test speed from enabling/disabling TCSM. That may be a good thing to look 
> into while optimizing JSC test speed.
> 
> - Alexey
> 
> 
>> As for non-JSC test runs, I have not actually measured what the time 
>> savings are.  Given there is resistance to going with O3 there, we don’t 
>> have to share the build artifacts for running the tests.  JSC test runs 
>> should be able to just build JSC for each O3 Debug JSC test run and it 
>> is still a win over the current status quo i.e. test runs never complete.
>> 
>> Regarding Geoff’s earlier question about whether I know for sure that 
>> switching to O3 will fix the current Debug JSC bot failures to run 
>> tests, the answer is I’m not certain.  The failure is a timeout due to 
>> the master bot not seeing any output from the tester bot for more than 
>> 20 minutes.  I’ve not been able to reproduce this yet.  But with a Debug 
>> build test run taking 4+ hours, it can only be a progression to switch 
>> the Debug JSC test bots to O3.
>> 
>> Mark
>> 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Saam Barati]

If we're only doing this for JSC, I don't think we need this, as none of us 
care.

If we want to do it for all of WK testing, we should include this for folks who 
care about having O0-style stack traces.

- Saam

> On Jun 24, 2020, at 12:17 PM, Geoffrey Garen  wrote:
> 
> Is "-fno-inline -fno-optimize-sibling-calls” still on the table?
> 
> Thanks,
> Geoff
> 
>> On Jun 24, 2020, at 10:28 AM, Mark Lam > > wrote:
>> 
>> I forgot to add ...
>> 
>>> On Jun 24, 2020, at 10:26 AM, Mark Lam >> > wrote:
>>> 
>>> Based on all the feedback given so far, it looks like we can move forward 
>>> with the following plan:
>>> 1. JSC Debug test bots will build their own local jsc with O3 before 
>>> running the tests.
>> 
>> 1.5 JSC EWS bot will also run with an O3 Debug build.
>> 
>> Mark
>> 
>>> 2. The rest of the build and test bots will remain unchanged.
>>> 
>>> Let's move forward with this and get the Debug JSC test bot functional 
>>> again.
>>> 
>>> Thanks.
>>> 
>>> Mark
>>> 
>>> 
 On Jun 19, 2020, at 2:58 PM, Alexey Proskuryakov >>> > wrote:
 
 
 
> 19 июня 2020 г., в 1:11 PM, Mark Lam  > написал(а):
> 
> 
> 
>> On Jun 19, 2020, at 10:24 AM, Geoffrey Garen > > wrote:
>> 
 On Jun 19, 2020, at 8:04 AM, Geoffrey Garen >>> > wrote:
 
 Can you explain more about what "O3 with no-inlining” is? How does 
 --force-opt=O3 avoid inlining? Would this fully resolve Simon concern 
 about stack traces, or would something still be different about stack 
 traces?
>>> There doesn't exist a way to do this now, but it'd be trivial to add a 
>>> way. I won't claim it fixes all stack traces differences, but I'd think 
>>> compiling using "-fno-inline -fno-optimize-sibling-calls" would get us 
>>> pretty far in crashing stack traces being similar enough.
>> 
>> Sounds good.
>> 
>> I think we should try to refine the proposal along these lines, to 
>> minimize the downsides. I won’t speak for Simon, but for me, being able 
>> to ensure a clear backtrace from a bot would be a big improvement.
>> 
 And again, I think this discussion would get a lot more focused if the 
 change could apply only to JSC code, and not also to WTF code.
>>> I believe Mark's proposal, initially, is just to make JSC do this. So I 
>>> don't see the point of compiling WTF differently. JSC can kick off its 
>>> own build, and run Debug+O3 tests faster than it can run Debug+O0 
>>> tests. Given people working on JSC want this, and people working on JSC 
>>> defend these tests, and that these test results are more stable (see 
>>> below), we should make this change for JSC.
>>> 
>>> I was trying to convince folks defending non-JSC testing, that they 
>>> too, should want this. I'm not going to pull teeth here. If folks want 
>>> their tests to take ~10x longer to run, they're entitled to make that 
>>> tradeoff.
>> 
>> Got it.
> 
> I'm of the same mind as Saam.  We want this change for the JSC bots, and 
> from the time measurements I’ve collected, we can afford to do a clean 
> build for the JSC Debug test runs using O3, and still come out way ahead.
 
 This seems like a reasonable plan. You didn't mention what hardware you 
 measured with, but it seems certain to be beneficial on any current 
 hardware.
 
 I need to mention that we saw unexplained and very large impact on JSC 
 test speed from enabling/disabling TCSM. That may be a good thing to look 
 into while optimizing JSC test speed.
 
 - Alexey
 
 
> As for non-JSC test runs, I have not actually measured what the time 
> savings are.  Given there is resistance to going with O3 there, we don’t 
> have to share the build artifacts for running the tests.  JSC test runs 
> should be able to just build JSC for each O3 Debug JSC test run and it is 
> still a win over the current status quo i.e. test runs never complete.
> 
> Regarding Geoff’s earlier question about whether I know for sure that 
> switching to O3 will fix the current Debug JSC bot failures to run tests, 
> the answer is I’m not certain.  The failure is a timeout due to the 
> master bot not seeing any output from the tester bot for more than 20 
> minutes.  I’ve not been able to reproduce this yet.  But with a Debug 
> build test run taking 4+ hours, it can only be a progression to switch 
> the Debug JSC test bots to O3.
> 
> Mark
> 
> 
>> 
 And again, on the run more tests front, it would be helpful to know 
 whether this change was enough to get the stress tests running or not.
>>> My experience running the tests locally 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Geoffrey Garen]

Is "-fno-inline -fno-optimize-sibling-calls” still on the table?

Thanks,
Geoff

> On Jun 24, 2020, at 10:28 AM, Mark Lam  wrote:
> 
> I forgot to add ...
> 
>> On Jun 24, 2020, at 10:26 AM, Mark Lam > > wrote:
>> 
>> Based on all the feedback given so far, it looks like we can move forward 
>> with the following plan:
>> 1. JSC Debug test bots will build their own local jsc with O3 before running 
>> the tests.
> 
> 1.5 JSC EWS bot will also run with an O3 Debug build.
> 
> Mark
> 
>> 2. The rest of the build and test bots will remain unchanged.
>> 
>> Let's move forward with this and get the Debug JSC test bot functional again.
>> 
>> Thanks.
>> 
>> Mark
>> 
>> 
>>> On Jun 19, 2020, at 2:58 PM, Alexey Proskuryakov >> > wrote:
>>> 
>>> 
>>> 
 19 июня 2020 г., в 1:11 PM, Mark Lam >>> > написал(а):
 
 
 
> On Jun 19, 2020, at 10:24 AM, Geoffrey Garen  > wrote:
> 
>>> On Jun 19, 2020, at 8:04 AM, Geoffrey Garen >> > wrote:
>>> 
>>> Can you explain more about what "O3 with no-inlining” is? How does 
>>> --force-opt=O3 avoid inlining? Would this fully resolve Simon concern 
>>> about stack traces, or would something still be different about stack 
>>> traces?
>> There doesn't exist a way to do this now, but it'd be trivial to add a 
>> way. I won't claim it fixes all stack traces differences, but I'd think 
>> compiling using "-fno-inline -fno-optimize-sibling-calls" would get us 
>> pretty far in crashing stack traces being similar enough.
> 
> Sounds good.
> 
> I think we should try to refine the proposal along these lines, to 
> minimize the downsides. I won’t speak for Simon, but for me, being able 
> to ensure a clear backtrace from a bot would be a big improvement.
> 
>>> And again, I think this discussion would get a lot more focused if the 
>>> change could apply only to JSC code, and not also to WTF code.
>> I believe Mark's proposal, initially, is just to make JSC do this. So I 
>> don't see the point of compiling WTF differently. JSC can kick off its 
>> own build, and run Debug+O3 tests faster than it can run Debug+O0 tests. 
>> Given people working on JSC want this, and people working on JSC defend 
>> these tests, and that these test results are more stable (see below), we 
>> should make this change for JSC.
>> 
>> I was trying to convince folks defending non-JSC testing, that they too, 
>> should want this. I'm not going to pull teeth here. If folks want their 
>> tests to take ~10x longer to run, they're entitled to make that tradeoff.
> 
> Got it.
 
 I'm of the same mind as Saam.  We want this change for the JSC bots, and 
 from the time measurements I’ve collected, we can afford to do a clean 
 build for the JSC Debug test runs using O3, and still come out way ahead.
>>> 
>>> This seems like a reasonable plan. You didn't mention what hardware you 
>>> measured with, but it seems certain to be beneficial on any current 
>>> hardware.
>>> 
>>> I need to mention that we saw unexplained and very large impact on JSC test 
>>> speed from enabling/disabling TCSM. That may be a good thing to look into 
>>> while optimizing JSC test speed.
>>> 
>>> - Alexey
>>> 
>>> 
 As for non-JSC test runs, I have not actually measured what the time 
 savings are.  Given there is resistance to going with O3 there, we don’t 
 have to share the build artifacts for running the tests.  JSC test runs 
 should be able to just build JSC for each O3 Debug JSC test run and it is 
 still a win over the current status quo i.e. test runs never complete.
 
 Regarding Geoff’s earlier question about whether I know for sure that 
 switching to O3 will fix the current Debug JSC bot failures to run tests, 
 the answer is I’m not certain.  The failure is a timeout due to the master 
 bot not seeing any output from the tester bot for more than 20 minutes.  
 I’ve not been able to reproduce this yet.  But with a Debug build test run 
 taking 4+ hours, it can only be a progression to switch the Debug JSC test 
 bots to O3.
 
 Mark
 
 
> 
>>> And again, on the run more tests front, it would be helpful to know 
>>> whether this change was enough to get the stress tests running or not.
>> My experience running the tests locally supports this fully. I don't get 
>> timeouts when running O3+Debug locally. When running Debug+O0 locally, 
>> I'd get timeouts all the time, and the total test run would take ~4-8 
>> hours. We can wait for official confirmation from Mark.
> 
> Alexey, do the JSC stress tests run now on bots? If not, how fast would 
> they need to run in order to be eligible to run on bots?
> 
> Thanks,
> Geoff
> 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Mark Lam]

I forgot to add ...

> On Jun 24, 2020, at 10:26 AM, Mark Lam  wrote:
> 
> Based on all the feedback given so far, it looks like we can move forward 
> with the following plan:
> 1. JSC Debug test bots will build their own local jsc with O3 before running 
> the tests.

1.5 JSC EWS bot will also run with an O3 Debug build.

Mark

> 2. The rest of the build and test bots will remain unchanged.
> 
> Let's move forward with this and get the Debug JSC test bot functional again.
> 
> Thanks.
> 
> Mark
> 
> 
>> On Jun 19, 2020, at 2:58 PM, Alexey Proskuryakov > > wrote:
>> 
>> 
>> 
>>> 19 июня 2020 г., в 1:11 PM, Mark Lam >> > написал(а):
>>> 
>>> 
>>> 
 On Jun 19, 2020, at 10:24 AM, Geoffrey Garen >>> > wrote:
 
>> On Jun 19, 2020, at 8:04 AM, Geoffrey Garen > > wrote:
>> 
>> Can you explain more about what "O3 with no-inlining” is? How does 
>> --force-opt=O3 avoid inlining? Would this fully resolve Simon concern 
>> about stack traces, or would something still be different about stack 
>> traces?
> There doesn't exist a way to do this now, but it'd be trivial to add a 
> way. I won't claim it fixes all stack traces differences, but I'd think 
> compiling using "-fno-inline -fno-optimize-sibling-calls" would get us 
> pretty far in crashing stack traces being similar enough.
 
 Sounds good.
 
 I think we should try to refine the proposal along these lines, to 
 minimize the downsides. I won’t speak for Simon, but for me, being able to 
 ensure a clear backtrace from a bot would be a big improvement.
 
>> And again, I think this discussion would get a lot more focused if the 
>> change could apply only to JSC code, and not also to WTF code.
> I believe Mark's proposal, initially, is just to make JSC do this. So I 
> don't see the point of compiling WTF differently. JSC can kick off its 
> own build, and run Debug+O3 tests faster than it can run Debug+O0 tests. 
> Given people working on JSC want this, and people working on JSC defend 
> these tests, and that these test results are more stable (see below), we 
> should make this change for JSC.
> 
> I was trying to convince folks defending non-JSC testing, that they too, 
> should want this. I'm not going to pull teeth here. If folks want their 
> tests to take ~10x longer to run, they're entitled to make that tradeoff.
 
 Got it.
>>> 
>>> I'm of the same mind as Saam.  We want this change for the JSC bots, and 
>>> from the time measurements I’ve collected, we can afford to do a clean 
>>> build for the JSC Debug test runs using O3, and still come out way ahead.
>> 
>> This seems like a reasonable plan. You didn't mention what hardware you 
>> measured with, but it seems certain to be beneficial on any current hardware.
>> 
>> I need to mention that we saw unexplained and very large impact on JSC test 
>> speed from enabling/disabling TCSM. That may be a good thing to look into 
>> while optimizing JSC test speed.
>> 
>> - Alexey
>> 
>> 
>>> As for non-JSC test runs, I have not actually measured what the time 
>>> savings are.  Given there is resistance to going with O3 there, we don’t 
>>> have to share the build artifacts for running the tests.  JSC test runs 
>>> should be able to just build JSC for each O3 Debug JSC test run and it is 
>>> still a win over the current status quo i.e. test runs never complete.
>>> 
>>> Regarding Geoff’s earlier question about whether I know for sure that 
>>> switching to O3 will fix the current Debug JSC bot failures to run tests, 
>>> the answer is I’m not certain.  The failure is a timeout due to the master 
>>> bot not seeing any output from the tester bot for more than 20 minutes.  
>>> I’ve not been able to reproduce this yet.  But with a Debug build test run 
>>> taking 4+ hours, it can only be a progression to switch the Debug JSC test 
>>> bots to O3.
>>> 
>>> Mark
>>> 
>>> 
 
>> And again, on the run more tests front, it would be helpful to know 
>> whether this change was enough to get the stress tests running or not.
> My experience running the tests locally supports this fully. I don't get 
> timeouts when running O3+Debug locally. When running Debug+O0 locally, 
> I'd get timeouts all the time, and the total test run would take ~4-8 
> hours. We can wait for official confirmation from Mark.
 
 Alexey, do the JSC stress tests run now on bots? If not, how fast would 
 they need to run in order to be eligible to run on bots?
 
 Thanks,
 Geoff
 
> 
> - Saam
> 
>> 
>> Thanks,
>> Geoff
>> 
>>> On Jun 18, 2020, at 9:30 PM, Saam Barati >> > wrote:
>>> 
>>> Why are we insisting on doing something on the bots that takes ~10x 
>>> longer to run than necessary? 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Mark Lam]

Based on all the feedback given so far, it looks like we can move forward with 
the following plan:
1. JSC Debug test bots will build their own local jsc with O3 before running 
the tests.
2. The rest of the build and test bots will remain unchanged.

Let's move forward with this and get the Debug JSC test bot functional again.

Thanks.

Mark


> On Jun 19, 2020, at 2:58 PM, Alexey Proskuryakov  wrote:
> 
> 
> 
>> 19 июня 2020 г., в 1:11 PM, Mark Lam > > написал(а):
>> 
>> 
>> 
>>> On Jun 19, 2020, at 10:24 AM, Geoffrey Garen >> > wrote:
>>> 
> On Jun 19, 2020, at 8:04 AM, Geoffrey Garen  > wrote:
> 
> Can you explain more about what "O3 with no-inlining” is? How does 
> --force-opt=O3 avoid inlining? Would this fully resolve Simon concern 
> about stack traces, or would something still be different about stack 
> traces?
 There doesn't exist a way to do this now, but it'd be trivial to add a 
 way. I won't claim it fixes all stack traces differences, but I'd think 
 compiling using "-fno-inline -fno-optimize-sibling-calls" would get us 
 pretty far in crashing stack traces being similar enough.
>>> 
>>> Sounds good.
>>> 
>>> I think we should try to refine the proposal along these lines, to minimize 
>>> the downsides. I won’t speak for Simon, but for me, being able to ensure a 
>>> clear backtrace from a bot would be a big improvement.
>>> 
> And again, I think this discussion would get a lot more focused if the 
> change could apply only to JSC code, and not also to WTF code.
 I believe Mark's proposal, initially, is just to make JSC do this. So I 
 don't see the point of compiling WTF differently. JSC can kick off its own 
 build, and run Debug+O3 tests faster than it can run Debug+O0 tests. Given 
 people working on JSC want this, and people working on JSC defend these 
 tests, and that these test results are more stable (see below), we should 
 make this change for JSC.
 
 I was trying to convince folks defending non-JSC testing, that they too, 
 should want this. I'm not going to pull teeth here. If folks want their 
 tests to take ~10x longer to run, they're entitled to make that tradeoff.
>>> 
>>> Got it.
>> 
>> I'm of the same mind as Saam.  We want this change for the JSC bots, and 
>> from the time measurements I’ve collected, we can afford to do a clean build 
>> for the JSC Debug test runs using O3, and still come out way ahead.
> 
> This seems like a reasonable plan. You didn't mention what hardware you 
> measured with, but it seems certain to be beneficial on any current hardware.
> 
> I need to mention that we saw unexplained and very large impact on JSC test 
> speed from enabling/disabling TCSM. That may be a good thing to look into 
> while optimizing JSC test speed.
> 
> - Alexey
> 
> 
>> As for non-JSC test runs, I have not actually measured what the time savings 
>> are.  Given there is resistance to going with O3 there, we don’t have to 
>> share the build artifacts for running the tests.  JSC test runs should be 
>> able to just build JSC for each O3 Debug JSC test run and it is still a win 
>> over the current status quo i.e. test runs never complete.
>> 
>> Regarding Geoff’s earlier question about whether I know for sure that 
>> switching to O3 will fix the current Debug JSC bot failures to run tests, 
>> the answer is I’m not certain.  The failure is a timeout due to the master 
>> bot not seeing any output from the tester bot for more than 20 minutes.  
>> I’ve not been able to reproduce this yet.  But with a Debug build test run 
>> taking 4+ hours, it can only be a progression to switch the Debug JSC test 
>> bots to O3.
>> 
>> Mark
>> 
>> 
>>> 
> And again, on the run more tests front, it would be helpful to know 
> whether this change was enough to get the stress tests running or not.
 My experience running the tests locally supports this fully. I don't get 
 timeouts when running O3+Debug locally. When running Debug+O0 locally, I'd 
 get timeouts all the time, and the total test run would take ~4-8 hours. 
 We can wait for official confirmation from Mark.
>>> 
>>> Alexey, do the JSC stress tests run now on bots? If not, how fast would 
>>> they need to run in order to be eligible to run on bots?
>>> 
>>> Thanks,
>>> Geoff
>>> 
 
 - Saam
 
> 
> Thanks,
> Geoff
> 
>> On Jun 18, 2020, at 9:30 PM, Saam Barati > > wrote:
>> 
>> Why are we insisting on doing something on the bots that takes ~10x 
>> longer to run than necessary? I’d rather have that time spent running 
>> more tests.
>> 
>> Overall, how we’re doing things now feels like a bad allocation of bot 
>> resources. The differences I see between O3 with no-inlining vs O0 is:
>> - Some race conditions will behave differently. Race 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Alexey Proskuryakov]

> 19 июня 2020 г., в 1:11 PM, Mark Lam  написал(а):
> 
> 
> 
>> On Jun 19, 2020, at 10:24 AM, Geoffrey Garen > > wrote:
>> 
 On Jun 19, 2020, at 8:04 AM, Geoffrey Garen >>> > wrote:
 
 Can you explain more about what "O3 with no-inlining” is? How does 
 --force-opt=O3 avoid inlining? Would this fully resolve Simon concern 
 about stack traces, or would something still be different about stack 
 traces?
>>> There doesn't exist a way to do this now, but it'd be trivial to add a way. 
>>> I won't claim it fixes all stack traces differences, but I'd think 
>>> compiling using "-fno-inline -fno-optimize-sibling-calls" would get us 
>>> pretty far in crashing stack traces being similar enough.
>> 
>> Sounds good.
>> 
>> I think we should try to refine the proposal along these lines, to minimize 
>> the downsides. I won’t speak for Simon, but for me, being able to ensure a 
>> clear backtrace from a bot would be a big improvement.
>> 
 And again, I think this discussion would get a lot more focused if the 
 change could apply only to JSC code, and not also to WTF code.
>>> I believe Mark's proposal, initially, is just to make JSC do this. So I 
>>> don't see the point of compiling WTF differently. JSC can kick off its own 
>>> build, and run Debug+O3 tests faster than it can run Debug+O0 tests. Given 
>>> people working on JSC want this, and people working on JSC defend these 
>>> tests, and that these test results are more stable (see below), we should 
>>> make this change for JSC.
>>> 
>>> I was trying to convince folks defending non-JSC testing, that they too, 
>>> should want this. I'm not going to pull teeth here. If folks want their 
>>> tests to take ~10x longer to run, they're entitled to make that tradeoff.
>> 
>> Got it.
> 
> I'm of the same mind as Saam.  We want this change for the JSC bots, and from 
> the time measurements I’ve collected, we can afford to do a clean build for 
> the JSC Debug test runs using O3, and still come out way ahead.

This seems like a reasonable plan. You didn't mention what hardware you 
measured with, but it seems certain to be beneficial on any current hardware.

I need to mention that we saw unexplained and very large impact on JSC test 
speed from enabling/disabling TCSM. That may be a good thing to look into while 
optimizing JSC test speed.

- Alexey


> As for non-JSC test runs, I have not actually measured what the time savings 
> are.  Given there is resistance to going with O3 there, we don’t have to 
> share the build artifacts for running the tests.  JSC test runs should be 
> able to just build JSC for each O3 Debug JSC test run and it is still a win 
> over the current status quo i.e. test runs never complete.
> 
> Regarding Geoff’s earlier question about whether I know for sure that 
> switching to O3 will fix the current Debug JSC bot failures to run tests, the 
> answer is I’m not certain.  The failure is a timeout due to the master bot 
> not seeing any output from the tester bot for more than 20 minutes.  I’ve not 
> been able to reproduce this yet.  But with a Debug build test run taking 4+ 
> hours, it can only be a progression to switch the Debug JSC test bots to O3.
> 
> Mark
> 
> 
>> 
 And again, on the run more tests front, it would be helpful to know 
 whether this change was enough to get the stress tests running or not.
>>> My experience running the tests locally supports this fully. I don't get 
>>> timeouts when running O3+Debug locally. When running Debug+O0 locally, I'd 
>>> get timeouts all the time, and the total test run would take ~4-8 hours. We 
>>> can wait for official confirmation from Mark.
>> 
>> Alexey, do the JSC stress tests run now on bots? If not, how fast would they 
>> need to run in order to be eligible to run on bots?
>> 
>> Thanks,
>> Geoff
>> 
>>> 
>>> - Saam
>>> 
 
 Thanks,
 Geoff
 
> On Jun 18, 2020, at 9:30 PM, Saam Barati  > wrote:
> 
> Why are we insisting on doing something on the bots that takes ~10x 
> longer to run than necessary? I’d rather have that time spent running 
> more tests.
> 
> Overall, how we’re doing things now feels like a bad allocation of bot 
> resources. The differences I see between O3 with no-inlining vs O0 is:
> - Some race conditions will behave differently. Race conditions are 
> already non predictable. I don’t think we’re losing anything here.
> - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t 
> in O0, and vice versa. In general, we probably care more about O3 
> compiler bugs than O0, since we don’t ship O0, but ship a lot of O3.
> 
> (And if we’re going to insist on “I want it to run what I build at my 
> desk”: I run debug with O3 at my desk, and I can run debug tests in a 
> reasonable amount of time now.)
> 
> In evaluating what’s the better 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Mark Lam]

> On Jun 19, 2020, at 1:04 PM, Alexey Proskuryakov  wrote:
> 
> 
> 
>> 19 июня 2020 г., в 10:24 AM, Geoffrey Garen > > написал(а):
>> 
 On Jun 19, 2020, at 8:04 AM, Geoffrey Garen >>> > wrote:
 
 Can you explain more about what "O3 with no-inlining” is? How does 
 --force-opt=O3 avoid inlining? Would this fully resolve Simon concern 
 about stack traces, or would something still be different about stack 
 traces?
>>> There doesn't exist a way to do this now, but it'd be trivial to add a way. 
>>> I won't claim it fixes all stack traces differences, but I'd think 
>>> compiling using "-fno-inline -fno-optimize-sibling-calls" would get us 
>>> pretty far in crashing stack traces being similar enough.
>> 
>> Sounds good.
>> 
>> I think we should try to refine the proposal along these lines, to minimize 
>> the downsides. I won’t speak for Simon, but for me, being able to ensure a 
>> clear backtrace from a bot would be a big improvement.
> 
> Enabling some level of optimization is reasonable; whether it should be -O3 
> with inlining disabled or -Og is a technical question that probably can't be 
> answered without hard data. Also, building locally in the same way as bots do 
> could be a show stopper, as people don't like slow builds.

I just sent an email with the hard data a few minutes ago.  -Og is 3.5x slower 
than -O3 on a Debug test run.

Building locally is totally acceptable.  It adds 6 minutes to the total test 
run time.  This is coming from a current run that takes 4.7 hours and will be 
reduced to about 45 minutes for a local build + O3 Debug test run.

> 
 And again, I think this discussion would get a lot more focused if the 
 change could apply only to JSC code, and not also to WTF code.
>>> I believe Mark's proposal, initially, is just to make JSC do this. So I 
>>> don't see the point of compiling WTF differently. JSC can kick off its own 
>>> build, and run Debug+O3 tests faster than it can run Debug+O0 tests. Given 
>>> people working on JSC want this, and people working on JSC defend these 
>>> tests, and that these test results are more stable (see below), we should 
>>> make this change for JSC.
>>> 
>>> I was trying to convince folks defending non-JSC testing, that they too, 
>>> should want this. I'm not going to pull teeth here. If folks want their 
>>> tests to take ~10x longer to run, they're entitled to make that tradeoff.
>> 
>> Got it.
> 
> To do this only for JSC builds, we'd need separate builders and storage, so 
> it becomes a question of allocating more resources, not just switching over 
> to a different configuration. While EWS builds for JSC independently, 
> post-commit testing shares build artifacts across all testers.

I don’t think we should go with separate storage unless there are other tests 
that also depend on a Debug JSC build.  Maybe I’m mistaken but I don’t think 
we’ll have any other reason to keep the build artifacts around.

While today’s post-commit test script for Debug JSC tests uses common build 
artifacts, why can’t we change the steps for this test to work like the EWS bot 
and just build locally?  In terms of total run time, even if we have a separate 
bot to build the binary, the test bot still has to wait for it because it would 
be a different build from the common build artifact that other test bots use.  
So, there is no time saved here.

Mark

 And again, on the run more tests front, it would be helpful to know 
 whether this change was enough to get the stress tests running or not.
>>> My experience running the tests locally supports this fully. I don't get 
>>> timeouts when running O3+Debug locally. When running Debug+O0 locally, I'd 
>>> get timeouts all the time, and the total test run would take ~4-8 hours. We 
>>> can wait for official confirmation from Mark.
>> 
>> Alexey, do the JSC stress tests run now on bots? If not, how fast would they 
>> need to run in order to be eligible to run on bots?
> 
> I don't think that there is a simple answer, as certain variations of stress 
> tests get disabled on certain bots, JSC tests have a lot of variations that 
> are handpicked. I wouldn't even know how to find the complex answer, but 
> perhaps you can get the answer from  >
> 
> - Alexey
> 
> 
> 
>> Thanks,
>> Geoff
>> 
>>> 
>>> - Saam
>>> 
 
 Thanks,
 Geoff
 
> On Jun 18, 2020, at 9:30 PM, Saam Barati  > wrote:
> 
> Why are we insisting on doing something on the bots that takes ~10x 
> longer to run than necessary? I’d rather have that time spent running 
> more tests.
> 
> Overall, how we’re doing things now feels like a bad allocation of bot 
> resources. The differences I see between O3 with no-inlining vs O0 is:
> - Some race conditions will behave differently. Race conditions are 
> 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Saam Barati]

> On Jun 19, 2020, at 1:04 PM, Alexey Proskuryakov  wrote:
> 
> 
> 
>> 19 июня 2020 г., в 10:24 AM, Geoffrey Garen > > написал(а):
>> 
 On Jun 19, 2020, at 8:04 AM, Geoffrey Garen >>> > wrote:
 
 Can you explain more about what "O3 with no-inlining” is? How does 
 --force-opt=O3 avoid inlining? Would this fully resolve Simon concern 
 about stack traces, or would something still be different about stack 
 traces?
>>> There doesn't exist a way to do this now, but it'd be trivial to add a way. 
>>> I won't claim it fixes all stack traces differences, but I'd think 
>>> compiling using "-fno-inline -fno-optimize-sibling-calls" would get us 
>>> pretty far in crashing stack traces being similar enough.
>> 
>> Sounds good.
>> 
>> I think we should try to refine the proposal along these lines, to minimize 
>> the downsides. I won’t speak for Simon, but for me, being able to ensure a 
>> clear backtrace from a bot would be a big improvement.
> 
> Enabling some level of optimization is reasonable; whether it should be -O3 
> with inlining disabled or -Og is a technical question that probably can't be 
> answered without hard data. Also, building locally in the same way as bots do 
> could be a show stopper, as people don't like slow builds.
Just to be super clear, I'm not proposing turning off inlining for JSC debug 
testers. We on JSC are happy with stack traces that aren't perfect.

My no inlining is a proposal for folks if we wanted this more broadly in our 
testing. I don't know what the results of inlining are on the time Debug+O3 
takes to. run. If it's negligible, we'd also be happy to run this way for JSC 
Debug. But if JSC is the only thing making a change, we're going to run with 
inlining on.

> 
 And again, I think this discussion would get a lot more focused if the 
 change could apply only to JSC code, and not also to WTF code.
>>> I believe Mark's proposal, initially, is just to make JSC do this. So I 
>>> don't see the point of compiling WTF differently. JSC can kick off its own 
>>> build, and run Debug+O3 tests faster than it can run Debug+O0 tests. Given 
>>> people working on JSC want this, and people working on JSC defend these 
>>> tests, and that these test results are more stable (see below), we should 
>>> make this change for JSC.
>>> 
>>> I was trying to convince folks defending non-JSC testing, that they too, 
>>> should want this. I'm not going to pull teeth here. If folks want their 
>>> tests to take ~10x longer to run, they're entitled to make that tradeoff.
>> 
>> Got it.
> 
> To do this only for JSC builds, we'd need separate builders and storage, so 
> it becomes a question of allocating more resources, not just switching over 
> to a different configuration. While EWS builds for JSC independently, 
> post-commit testing shares build artifacts across all testers.
As Mark has shown, we can build locally and run faster than using a plain debug 
build. So as a straw man, this should just work and be faster than what we have 
today.

- Saam


> 
 And again, on the run more tests front, it would be helpful to know 
 whether this change was enough to get the stress tests running or not.
>>> My experience running the tests locally supports this fully. I don't get 
>>> timeouts when running O3+Debug locally. When running Debug+O0 locally, I'd 
>>> get timeouts all the time, and the total test run would take ~4-8 hours. We 
>>> can wait for official confirmation from Mark.
>> 
>> Alexey, do the JSC stress tests run now on bots? If not, how fast would they 
>> need to run in order to be eligible to run on bots?
> 
> I don't think that there is a simple answer, as certain variations of stress 
> tests get disabled on certain bots, JSC tests have a lot of variations that 
> are handpicked. I wouldn't even know how to find the complex answer, but 
> perhaps you can get the answer from  >
> 
> - Alexey
> 
> 
> 
>> Thanks,
>> Geoff
>> 
>>> 
>>> - Saam
>>> 
 
 Thanks,
 Geoff
 
> On Jun 18, 2020, at 9:30 PM, Saam Barati  > wrote:
> 
> Why are we insisting on doing something on the bots that takes ~10x 
> longer to run than necessary? I’d rather have that time spent running 
> more tests.
> 
> Overall, how we’re doing things now feels like a bad allocation of bot 
> resources. The differences I see between O3 with no-inlining vs O0 is:
> - Some race conditions will behave differently. Race conditions are 
> already non predictable. I don’t think we’re losing anything here.
> - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t 
> in O0, and vice versa. In general, we probably care more about O3 
> compiler bugs than O0, since we don’t ship O0, but ship a lot of O3.
> 
> (And if we’re going to insist on “I 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Mark Lam]

> On Jun 19, 2020, at 10:24 AM, Geoffrey Garen  wrote:
> 
>>> On Jun 19, 2020, at 8:04 AM, Geoffrey Garen >> > wrote:
>>> 
>>> Can you explain more about what "O3 with no-inlining” is? How does 
>>> --force-opt=O3 avoid inlining? Would this fully resolve Simon concern about 
>>> stack traces, or would something still be different about stack traces?
>> There doesn't exist a way to do this now, but it'd be trivial to add a way. 
>> I won't claim it fixes all stack traces differences, but I'd think compiling 
>> using "-fno-inline -fno-optimize-sibling-calls" would get us pretty far in 
>> crashing stack traces being similar enough.
> 
> Sounds good.
> 
> I think we should try to refine the proposal along these lines, to minimize 
> the downsides. I won’t speak for Simon, but for me, being able to ensure a 
> clear backtrace from a bot would be a big improvement.
> 
>>> And again, I think this discussion would get a lot more focused if the 
>>> change could apply only to JSC code, and not also to WTF code.
>> I believe Mark's proposal, initially, is just to make JSC do this. So I 
>> don't see the point of compiling WTF differently. JSC can kick off its own 
>> build, and run Debug+O3 tests faster than it can run Debug+O0 tests. Given 
>> people working on JSC want this, and people working on JSC defend these 
>> tests, and that these test results are more stable (see below), we should 
>> make this change for JSC.
>> 
>> I was trying to convince folks defending non-JSC testing, that they too, 
>> should want this. I'm not going to pull teeth here. If folks want their 
>> tests to take ~10x longer to run, they're entitled to make that tradeoff.
> 
> Got it.

I'm of the same mind as Saam.  We want this change for the JSC bots, and from 
the time measurements I’ve collected, we can afford to do a clean build for the 
JSC Debug test runs using O3, and still come out way ahead.

As for non-JSC test runs, I have not actually measured what the time savings 
are.  Given there is resistance to going with O3 there, we don’t have to share 
the build artifacts for running the tests.  JSC test runs should be able to 
just build JSC for each O3 Debug JSC test run and it is still a win over the 
current status quo i.e. test runs never complete.

Regarding Geoff’s earlier question about whether I know for sure that switching 
to O3 will fix the current Debug JSC bot failures to run tests, the answer is 
I’m not certain.  The failure is a timeout due to the master bot not seeing any 
output from the tester bot for more than 20 minutes.  I’ve not been able to 
reproduce this yet.  But with a Debug build test run taking 4+ hours, it can 
only be a progression to switch the Debug JSC test bots to O3.

Mark


> 
>>> And again, on the run more tests front, it would be helpful to know whether 
>>> this change was enough to get the stress tests running or not.
>> My experience running the tests locally supports this fully. I don't get 
>> timeouts when running O3+Debug locally. When running Debug+O0 locally, I'd 
>> get timeouts all the time, and the total test run would take ~4-8 hours. We 
>> can wait for official confirmation from Mark.
> 
> Alexey, do the JSC stress tests run now on bots? If not, how fast would they 
> need to run in order to be eligible to run on bots?
> 
> Thanks,
> Geoff
> 
>> 
>> - Saam
>> 
>>> 
>>> Thanks,
>>> Geoff
>>> 
 On Jun 18, 2020, at 9:30 PM, Saam Barati >>> > wrote:
 
 Why are we insisting on doing something on the bots that takes ~10x longer 
 to run than necessary? I’d rather have that time spent running more tests.
 
 Overall, how we’re doing things now feels like a bad allocation of bot 
 resources. The differences I see between O3 with no-inlining vs O0 is:
 - Some race conditions will behave differently. Race conditions are 
 already non predictable. I don’t think we’re losing anything here.
 - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t 
 in O0, and vice versa. In general, we probably care more about O3 compiler 
 bugs than O0, since we don’t ship O0, but ship a lot of O3.
 
 (And if we’re going to insist on “I want it to run what I build at my 
 desk”: I run debug with O3 at my desk, and I can run debug tests in a 
 reasonable amount of time now.)
 
 In evaluating what’s the better setup, I think it’s helpful to think about 
 this from the other side. Let’s imagine we had Debug+O3 as our current 
 setup. And someone proposed to move it to O0 and make our tests take ~10x 
 longer. I think that’d be a non-starter.
 
 - Saam
 
> On Jun 17, 2020, at 9:48 PM, Simon Fraser  > wrote:
> 
> I also object to losing good stack traces for crashes on Debug bots.
> 
> Also, I don't think Debug bots should build something different from what 
> I build at my desk.
> 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Alexey Proskuryakov]

> 19 июня 2020 г., в 10:24 AM, Geoffrey Garen  написал(а):
> 
>>> On Jun 19, 2020, at 8:04 AM, Geoffrey Garen >> > wrote:
>>> 
>>> Can you explain more about what "O3 with no-inlining” is? How does 
>>> --force-opt=O3 avoid inlining? Would this fully resolve Simon concern about 
>>> stack traces, or would something still be different about stack traces?
>> There doesn't exist a way to do this now, but it'd be trivial to add a way. 
>> I won't claim it fixes all stack traces differences, but I'd think compiling 
>> using "-fno-inline -fno-optimize-sibling-calls" would get us pretty far in 
>> crashing stack traces being similar enough.
> 
> Sounds good.
> 
> I think we should try to refine the proposal along these lines, to minimize 
> the downsides. I won’t speak for Simon, but for me, being able to ensure a 
> clear backtrace from a bot would be a big improvement.

Enabling some level of optimization is reasonable; whether it should be -O3 
with inlining disabled or -Og is a technical question that probably can't be 
answered without hard data. Also, building locally in the same way as bots do 
could be a show stopper, as people don't like slow builds.

>>> And again, I think this discussion would get a lot more focused if the 
>>> change could apply only to JSC code, and not also to WTF code.
>> I believe Mark's proposal, initially, is just to make JSC do this. So I 
>> don't see the point of compiling WTF differently. JSC can kick off its own 
>> build, and run Debug+O3 tests faster than it can run Debug+O0 tests. Given 
>> people working on JSC want this, and people working on JSC defend these 
>> tests, and that these test results are more stable (see below), we should 
>> make this change for JSC.
>> 
>> I was trying to convince folks defending non-JSC testing, that they too, 
>> should want this. I'm not going to pull teeth here. If folks want their 
>> tests to take ~10x longer to run, they're entitled to make that tradeoff.
> 
> Got it.

To do this only for JSC builds, we'd need separate builders and storage, so it 
becomes a question of allocating more resources, not just switching over to a 
different configuration. While EWS builds for JSC independently, post-commit 
testing shares build artifacts across all testers.

>>> And again, on the run more tests front, it would be helpful to know whether 
>>> this change was enough to get the stress tests running or not.
>> My experience running the tests locally supports this fully. I don't get 
>> timeouts when running O3+Debug locally. When running Debug+O0 locally, I'd 
>> get timeouts all the time, and the total test run would take ~4-8 hours. We 
>> can wait for official confirmation from Mark.
> 
> Alexey, do the JSC stress tests run now on bots? If not, how fast would they 
> need to run in order to be eligible to run on bots?

I don't think that there is a simple answer, as certain variations of stress 
tests get disabled on certain bots, JSC tests have a lot of variations that are 
handpicked. I wouldn't even know how to find the complex answer, but perhaps 
you can get the answer from 

- Alexey



> Thanks,
> Geoff
> 
>> 
>> - Saam
>> 
>>> 
>>> Thanks,
>>> Geoff
>>> 
 On Jun 18, 2020, at 9:30 PM, Saam Barati >>> > wrote:
 
 Why are we insisting on doing something on the bots that takes ~10x longer 
 to run than necessary? I’d rather have that time spent running more tests.
 
 Overall, how we’re doing things now feels like a bad allocation of bot 
 resources. The differences I see between O3 with no-inlining vs O0 is:
 - Some race conditions will behave differently. Race conditions are 
 already non predictable. I don’t think we’re losing anything here.
 - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t 
 in O0, and vice versa. In general, we probably care more about O3 compiler 
 bugs than O0, since we don’t ship O0, but ship a lot of O3.
 
 (And if we’re going to insist on “I want it to run what I build at my 
 desk”: I run debug with O3 at my desk, and I can run debug tests in a 
 reasonable amount of time now.)
 
 In evaluating what’s the better setup, I think it’s helpful to think about 
 this from the other side. Let’s imagine we had Debug+O3 as our current 
 setup. And someone proposed to move it to O0 and make our tests take ~10x 
 longer. I think that’d be a non-starter.
 
 - Saam
 
> On Jun 17, 2020, at 9:48 PM, Simon Fraser  > wrote:
> 
> I also object to losing good stack traces for crashes on Debug bots.
> 
> Also, I don't think Debug bots should build something different from what 
> I build at my desk.
> 
> Simon
> 
>> On Jun 17, 2020, at 1:36 PM, Mark Lam > > wrote:
>> 
>> Hi folks,
>> 
>> We're 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Mark Lam]

> On Jun 19, 2020, at 10:02 AM, Alexey Proskuryakov  wrote:
> 
> 
> 
>> 19 июня 2020 г., в 9:59 AM, Mark Lam > > написал(а):
>> 
>> 
>> 
>>> On Jun 19, 2020, at 9:53 AM, Alexey Proskuryakov >> > wrote:
>>> 
>>> 
>>> 
 18 июня 2020 г., в 9:30 PM, Saam Barati >>> > написал(а):
 
 Why are we insisting on doing something on the bots that takes ~10x longer 
 to run than necessary? I’d rather have that time spent running more tests.
>>> 
>>> Replying to this point specifically, I wanted to point out that WebKit 
>>> tests take 2x longer in debug, not 10x longer. JSC tests take 3.6x longer.
>> 
>> Since I collected real data on this last night on the actual bot that runs 
>> the JSC stress tests, I’ll share the data here:
>> 
>> Build time
>> A clean build using buid-jsc for a normal Debug build on bot638 takes about 
>> 4.5 minutes.
>> A clean build using build-jsc for a --force-opt=O3 Debug build on bot638 
>> takes about 6 minutes.
>> 
>> Test run time
>> Running with a regular Debug build, the test completed in about 4 hours 41 
>> minutes with 1 timeout.
>> Running with a --force-opt=O3 Debug build, the test completed in about 39 
>> minutes with 0 timeouts.
>> 
>> The difference in test run time is 281 minutes vs 29 minutes.  That is a 
>> 7.2x ratio, not 3.6x.
> 
> https://build.webkit.org/builders/Apple-Catalina-Debug-JSC-Tests/builds/1080 
> 
>  - 4 hrs, 5 secs
> https://build.webkit.org/builders/Apple-Catalina-Release-JSC-Tests/builds/2546
>  
> 
>  - 1 hrs, 6 mins, 27 secs
> 
> That's 3.6x.

Some details to consider:

1. 
https://build.webkit.org/builders/Apple-Catalina-Release-JSC-Tests/builds/2546 

 runs on a different bot than 
https://build.webkit.org/builders/Apple-Catalina-Debug-JSC-Tests/builds/1080 
 .

2. You’re comparing a Release build run vs a Debug build run, not an O3 Debug 
build vs a regular Debug build.

3. Release builds do less work e.g. all debug ASSERTs are disabled.  Debug only 
validation code is disabled.

4. Not every file in a Release build is compiled with O3.  If I remember 
correctly, some are O3, others are not.  None are O0.

5. The collection of JSC tests run for Debug builds and Release builds are 
slightly different.  For example, Debug builds run 71793 jsc stress tests.  
Release builds runs 69950 jsc stress tests.  Hence, the Debug builds run 1843 
more tests.

My main point here is that Release builds are not the same as O3 Debug builds: 
some things are faster, some things are slower.  A Release build test run is at 
best an approximate representation of how a Debug O3 build test run will 
behave.  FWIW, my data came from actually running an O3 Debug build and a 
regular Debug build on the same bot.  

But my number are purely from timing the run of the tests.  If the numbers 
reported from the bot includes time for any bots scripts in addition to the 
test run times (I don’t know if there are any), then the total run time will 
also be different than the numbers I collected.  Feel free to use the 3.6x 
ratio if you prefer.

About -Og numbers (using the same measurement methology as my O3 Debug and 
regular Debug runs):

Build time: A clean build using build-jsc for a --force-opt=Og Debug build on 
bot638 takes about 5.5 minutes.
Test run time: Running with a --force-opt=Og Debug build, the test completed in 
about 2 hours 19 minute minutes with 0 timeouts.

That's about 3.5x slower than the Debug O3 run.

Mark


> 
> - Alexey
> 
> 
> 
 Overall, how we’re doing things now feels like a bad allocation of bot 
 resources. The differences I see between O3 with no-inlining vs O0 is:
>>> 
>>> Last time this was discussed, we talked about -Og, which is specifically 
>>> designed for the purpose I believe. Where do we stand on understanding and 
>>> adopting that?
>> 
>> I tried -Og last time after your suggestion, and I remember thinking that 
>> the perf was not acceptable back then.  I’ll collect the data again and 
>> report back with real number later today.
>> 
>> Mark
>> 
>>> 
>>> - Alexey
>>> 
 - Some race conditions will behave differently. Race conditions are 
 already non predictable. I don’t think we’re losing anything here.
 - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t 
 in O0, and vice versa. In general, we probably care more about O3 compiler 
 bugs than O0, since we don’t ship O0, but ship a lot of O3.
 
 (And if we’re going to insist on “I want it to run what I build at my 
 desk”: I run debug with O3 at my desk, and I can run debug tests in a 
 reasonable amount of time now.)

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Geoffrey Garen]

>> On Jun 19, 2020, at 8:04 AM, Geoffrey Garen > > wrote:
>> 
>> Can you explain more about what "O3 with no-inlining” is? How does 
>> --force-opt=O3 avoid inlining? Would this fully resolve Simon concern about 
>> stack traces, or would something still be different about stack traces?
> There doesn't exist a way to do this now, but it'd be trivial to add a way. I 
> won't claim it fixes all stack traces differences, but I'd think compiling 
> using "-fno-inline -fno-optimize-sibling-calls" would get us pretty far in 
> crashing stack traces being similar enough.

Sounds good.

I think we should try to refine the proposal along these lines, to minimize the 
downsides. I won’t speak for Simon, but for me, being able to ensure a clear 
backtrace from a bot would be a big improvement.

>> And again, I think this discussion would get a lot more focused if the 
>> change could apply only to JSC code, and not also to WTF code.
> I believe Mark's proposal, initially, is just to make JSC do this. So I don't 
> see the point of compiling WTF differently. JSC can kick off its own build, 
> and run Debug+O3 tests faster than it can run Debug+O0 tests. Given people 
> working on JSC want this, and people working on JSC defend these tests, and 
> that these test results are more stable (see below), we should make this 
> change for JSC.
> 
> I was trying to convince folks defending non-JSC testing, that they too, 
> should want this. I'm not going to pull teeth here. If folks want their tests 
> to take ~10x longer to run, they're entitled to make that tradeoff.

Got it.

>> And again, on the run more tests front, it would be helpful to know whether 
>> this change was enough to get the stress tests running or not.
> My experience running the tests locally supports this fully. I don't get 
> timeouts when running O3+Debug locally. When running Debug+O0 locally, I'd 
> get timeouts all the time, and the total test run would take ~4-8 hours. We 
> can wait for official confirmation from Mark.

Alexey, do the JSC stress tests run now on bots? If not, how fast would they 
need to run in order to be eligible to run on bots?

Thanks,
Geoff

> 
> - Saam
> 
>> 
>> Thanks,
>> Geoff
>> 
>>> On Jun 18, 2020, at 9:30 PM, Saam Barati >> > wrote:
>>> 
>>> Why are we insisting on doing something on the bots that takes ~10x longer 
>>> to run than necessary? I’d rather have that time spent running more tests.
>>> 
>>> Overall, how we’re doing things now feels like a bad allocation of bot 
>>> resources. The differences I see between O3 with no-inlining vs O0 is:
>>> - Some race conditions will behave differently. Race conditions are already 
>>> non predictable. I don’t think we’re losing anything here.
>>> - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t in 
>>> O0, and vice versa. In general, we probably care more about O3 compiler 
>>> bugs than O0, since we don’t ship O0, but ship a lot of O3.
>>> 
>>> (And if we’re going to insist on “I want it to run what I build at my 
>>> desk”: I run debug with O3 at my desk, and I can run debug tests in a 
>>> reasonable amount of time now.)
>>> 
>>> In evaluating what’s the better setup, I think it’s helpful to think about 
>>> this from the other side. Let’s imagine we had Debug+O3 as our current 
>>> setup. And someone proposed to move it to O0 and make our tests take ~10x 
>>> longer. I think that’d be a non-starter.
>>> 
>>> - Saam
>>> 
 On Jun 17, 2020, at 9:48 PM, Simon Fraser >>> > wrote:
 
 I also object to losing good stack traces for crashes on Debug bots.
 
 Also, I don't think Debug bots should build something different from what 
 I build at my desk.
 
 Simon
 
> On Jun 17, 2020, at 1:36 PM, Mark Lam  > wrote:
> 
> Hi folks,
> 
> We're planning to switch the JSC EWS bot and build.webkit.org 
>  Debug build and test bots to building with the 
> following set first:
> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
> 
> This means the Debug builds will be built with optimization level forced 
> to O3.
> 
> Why are we doing this?
> 1. So that the JSC EWS will start catching ASSERT failures.
> 2. JSC stress test Debug bots have been timing out and not running tests 
> at all.  Hopefully, this change will fix this issue.
> 3. Tests will run to completion faster and we’ll catch regressions sooner.
> 
> The downside: crash stack traces will be like Release build stack traces. 
>  But I don’t think we should let this deter us.  It’s not like there’s no 
> stack information.  And just as we do with debugging Release build test 
> failures, we can always do a Debug build locally to do our debugging.
> 
> We would like to apply this change to all Debug build and test bots, not 
> just 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Saam Barati]

> On Jun 19, 2020, at 10:02 AM, Saam Barati  wrote:
> 
> 
> 
>> On Jun 19, 2020, at 8:04 AM, Geoffrey Garen > > wrote:
>> 
>> Can you explain more about what "O3 with no-inlining” is? How does 
>> --force-opt=O3 avoid inlining? Would this fully resolve Simon concern about 
>> stack traces, or would something still be different about stack traces?
> There doesn't exist a way to do this now, but it'd be trivial to add a way. I 
> won't claim it fixes all stack traces differences, but I'd think compiling 
> using "-fno-inline -fno-optimize-sibling-calls" would get us pretty far in 
> crashing stack traces being similar enough.
> 
>> 
>> And again, I think this discussion would get a lot more focused if the 
>> change could apply only to JSC code, and not also to WTF code.
> I believe Mark's proposal, initially, is just to make JSC do this. So I don't 
> see the point of compiling WTF differently. JSC can kick off its own build, 
> and run Debug+O3 tests faster than it can run Debug+O0 tests. Given people 
> working on JSC want this, and people working on JSC defend these tests, and 
> that these test results are more stable (see below), we should make this 
> change for JSC.
> 
> I was trying to convince folks defending non-JSC testing, that they too, 
> should want this. I'm not going to pull teeth here. If folks want their tests 
> to take ~10x longer to run, they're entitled to make that tradeoff.
According to Alexey, this is ~2x longer. So please replace my use of 10x here 
with 2x.

- Saam

> 
>> 
>> And again, on the run more tests front, it would be helpful to know whether 
>> this change was enough to get the stress tests running or not.
> My experience running the tests locally supports this fully. I don't get 
> timeouts when running O3+Debug locally. When running Debug+O0 locally, I'd 
> get timeouts all the time, and the total test run would take ~4-8 hours. We 
> can wait for official confirmation from Mark.
> 
> - Saam
> 
>> 
>> Thanks,
>> Geoff
>> 
>>> On Jun 18, 2020, at 9:30 PM, Saam Barati >> > wrote:
>>> 
>>> Why are we insisting on doing something on the bots that takes ~10x longer 
>>> to run than necessary? I’d rather have that time spent running more tests.
>>> 
>>> Overall, how we’re doing things now feels like a bad allocation of bot 
>>> resources. The differences I see between O3 with no-inlining vs O0 is:
>>> - Some race conditions will behave differently. Race conditions are already 
>>> non predictable. I don’t think we’re losing anything here.
>>> - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t in 
>>> O0, and vice versa. In general, we probably care more about O3 compiler 
>>> bugs than O0, since we don’t ship O0, but ship a lot of O3.
>>> 
>>> (And if we’re going to insist on “I want it to run what I build at my 
>>> desk”: I run debug with O3 at my desk, and I can run debug tests in a 
>>> reasonable amount of time now.)
>>> 
>>> In evaluating what’s the better setup, I think it’s helpful to think about 
>>> this from the other side. Let’s imagine we had Debug+O3 as our current 
>>> setup. And someone proposed to move it to O0 and make our tests take ~10x 
>>> longer. I think that’d be a non-starter.
>>> 
>>> - Saam
>>> 
 On Jun 17, 2020, at 9:48 PM, Simon Fraser >>> > wrote:
 
 I also object to losing good stack traces for crashes on Debug bots.
 
 Also, I don't think Debug bots should build something different from what 
 I build at my desk.
 
 Simon
 
> On Jun 17, 2020, at 1:36 PM, Mark Lam  > wrote:
> 
> Hi folks,
> 
> We're planning to switch the JSC EWS bot and build.webkit.org 
>  Debug build and test bots to building with the 
> following set first:
> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
> 
> This means the Debug builds will be built with optimization level forced 
> to O3.
> 
> Why are we doing this?
> 1. So that the JSC EWS will start catching ASSERT failures.
> 2. JSC stress test Debug bots have been timing out and not running tests 
> at all.  Hopefully, this change will fix this issue.
> 3. Tests will run to completion faster and we’ll catch regressions sooner.
> 
> The downside: crash stack traces will be like Release build stack traces. 
>  But I don’t think we should let this deter us.  It’s not like there’s no 
> stack information.  And just as we do with debugging Release build test 
> failures, we can always do a Debug build locally to do our debugging.
> 
> We would like to apply this change to all Debug build and test bots, not 
> just the JSC ones.  Does anyone strongly object to this change?
> 
> Thanks.
> 
> Cheers,
> Mark
> 
> ___
> webkit-dev mailing list

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Alexey Proskuryakov]

> 19 июня 2020 г., в 9:59 AM, Mark Lam  написал(а):
> 
> 
> 
>> On Jun 19, 2020, at 9:53 AM, Alexey Proskuryakov > > wrote:
>> 
>> 
>> 
>>> 18 июня 2020 г., в 9:30 PM, Saam Barati >> > написал(а):
>>> 
>>> Why are we insisting on doing something on the bots that takes ~10x longer 
>>> to run than necessary? I’d rather have that time spent running more tests.
>> 
>> Replying to this point specifically, I wanted to point out that WebKit tests 
>> take 2x longer in debug, not 10x longer. JSC tests take 3.6x longer.
> 
> Since I collected real data on this last night on the actual bot that runs 
> the JSC stress tests, I’ll share the data here:
> 
> Build time
> A clean build using buid-jsc for a normal Debug build on bot638 takes about 
> 4.5 minutes.
> A clean build using build-jsc for a --force-opt=O3 Debug build on bot638 
> takes about 6 minutes.
> 
> Test run time
> Running with a regular Debug build, the test completed in about 4 hours 41 
> minutes with 1 timeout.
> Running with a --force-opt=O3 Debug build, the test completed in about 39 
> minutes with 0 timeouts.
> 
> The difference in test run time is 281 minutes vs 29 minutes.  That is a 7.2x 
> ratio, not 3.6x.

https://build.webkit.org/builders/Apple-Catalina-Debug-JSC-Tests/builds/1080 - 
4 hrs, 5 secs
https://build.webkit.org/builders/Apple-Catalina-Release-JSC-Tests/builds/2546 
- 1 hrs, 6 mins, 27 secs

That's 3.6x.

- Alexey



>>> Overall, how we’re doing things now feels like a bad allocation of bot 
>>> resources. The differences I see between O3 with no-inlining vs O0 is:
>> 
>> Last time this was discussed, we talked about -Og, which is specifically 
>> designed for the purpose I believe. Where do we stand on understanding and 
>> adopting that?
> 
> I tried -Og last time after your suggestion, and I remember thinking that the 
> perf was not acceptable back then.  I’ll collect the data again and report 
> back with real number later today.
> 
> Mark
> 
>> 
>> - Alexey
>> 
>>> - Some race conditions will behave differently. Race conditions are already 
>>> non predictable. I don’t think we’re losing anything here.
>>> - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t in 
>>> O0, and vice versa. In general, we probably care more about O3 compiler 
>>> bugs than O0, since we don’t ship O0, but ship a lot of O3.
>>> 
>>> (And if we’re going to insist on “I want it to run what I build at my 
>>> desk”: I run debug with O3 at my desk, and I can run debug tests in a 
>>> reasonable amount of time now.)
>>> 
>>> In evaluating what’s the better setup, I think it’s helpful to think about 
>>> this from the other side. Let’s imagine we had Debug+O3 as our current 
>>> setup. And someone proposed to move it to O0 and make our tests take ~10x 
>>> longer. I think that’d be a non-starter.
>>> 
>>> - Saam
>>> 
 On Jun 17, 2020, at 9:48 PM, Simon Fraser >>> > wrote:
 
 I also object to losing good stack traces for crashes on Debug bots.
 
 Also, I don't think Debug bots should build something different from what 
 I build at my desk.
 
 Simon
 
> On Jun 17, 2020, at 1:36 PM, Mark Lam  > wrote:
> 
> Hi folks,
> 
> We're planning to switch the JSC EWS bot and build.webkit.org 
>  Debug build and test bots to building with the 
> following set first:
> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
> 
> This means the Debug builds will be built with optimization level forced 
> to O3.
> 
> Why are we doing this?
> 1. So that the JSC EWS will start catching ASSERT failures.
> 2. JSC stress test Debug bots have been timing out and not running tests 
> at all.  Hopefully, this change will fix this issue.
> 3. Tests will run to completion faster and we’ll catch regressions sooner.
> 
> The downside: crash stack traces will be like Release build stack traces. 
>  But I don’t think we should let this deter us.  It’s not like there’s no 
> stack information.  And just as we do with debugging Release build test 
> failures, we can always do a Debug build locally to do our debugging.
> 
> We would like to apply this change to all Debug build and test bots, not 
> just the JSC ones.  Does anyone strongly object to this change?
> 
> Thanks.
> 
> Cheers,
> Mark
> 
> ___
> webkit-dev mailing list
> webkit-dev@lists.webkit.org 
> https://lists.webkit.org/mailman/listinfo/webkit-dev 
> 
 
 ___
 webkit-dev mailing list
 webkit-dev@lists.webkit.org 
 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Saam Barati]

> On Jun 19, 2020, at 8:04 AM, Geoffrey Garen  wrote:
> 
> Can you explain more about what "O3 with no-inlining” is? How does 
> --force-opt=O3 avoid inlining? Would this fully resolve Simon concern about 
> stack traces, or would something still be different about stack traces?
There doesn't exist a way to do this now, but it'd be trivial to add a way. I 
won't claim it fixes all stack traces differences, but I'd think compiling 
using "-fno-inline -fno-optimize-sibling-calls" would get us pretty far in 
crashing stack traces being similar enough.

> 
> And again, I think this discussion would get a lot more focused if the change 
> could apply only to JSC code, and not also to WTF code.
I believe Mark's proposal, initially, is just to make JSC do this. So I don't 
see the point of compiling WTF differently. JSC can kick off its own build, and 
run Debug+O3 tests faster than it can run Debug+O0 tests. Given people working 
on JSC want this, and people working on JSC defend these tests, and that these 
test results are more stable (see below), we should make this change for JSC.

I was trying to convince folks defending non-JSC testing, that they too, should 
want this. I'm not going to pull teeth here. If folks want their tests to take 
~10x longer to run, they're entitled to make that tradeoff.

> 
> And again, on the run more tests front, it would be helpful to know whether 
> this change was enough to get the stress tests running or not.
My experience running the tests locally supports this fully. I don't get 
timeouts when running O3+Debug locally. When running Debug+O0 locally, I'd get 
timeouts all the time, and the total test run would take ~4-8 hours. We can 
wait for official confirmation from Mark.

- Saam

> 
> Thanks,
> Geoff
> 
>> On Jun 18, 2020, at 9:30 PM, Saam Barati > > wrote:
>> 
>> Why are we insisting on doing something on the bots that takes ~10x longer 
>> to run than necessary? I’d rather have that time spent running more tests.
>> 
>> Overall, how we’re doing things now feels like a bad allocation of bot 
>> resources. The differences I see between O3 with no-inlining vs O0 is:
>> - Some race conditions will behave differently. Race conditions are already 
>> non predictable. I don’t think we’re losing anything here.
>> - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t in 
>> O0, and vice versa. In general, we probably care more about O3 compiler bugs 
>> than O0, since we don’t ship O0, but ship a lot of O3.
>> 
>> (And if we’re going to insist on “I want it to run what I build at my desk”: 
>> I run debug with O3 at my desk, and I can run debug tests in a reasonable 
>> amount of time now.)
>> 
>> In evaluating what’s the better setup, I think it’s helpful to think about 
>> this from the other side. Let’s imagine we had Debug+O3 as our current 
>> setup. And someone proposed to move it to O0 and make our tests take ~10x 
>> longer. I think that’d be a non-starter.
>> 
>> - Saam
>> 
>>> On Jun 17, 2020, at 9:48 PM, Simon Fraser >> > wrote:
>>> 
>>> I also object to losing good stack traces for crashes on Debug bots.
>>> 
>>> Also, I don't think Debug bots should build something different from what I 
>>> build at my desk.
>>> 
>>> Simon
>>> 
 On Jun 17, 2020, at 1:36 PM, Mark Lam >>> > wrote:
 
 Hi folks,
 
 We're planning to switch the JSC EWS bot and build.webkit.org 
  Debug build and test bots to building with the 
 following set first:
 ./Tools/Scripts/set-webkit-configuration --force-opt=O3
 
 This means the Debug builds will be built with optimization level forced 
 to O3.
 
 Why are we doing this?
 1. So that the JSC EWS will start catching ASSERT failures.
 2. JSC stress test Debug bots have been timing out and not running tests 
 at all.  Hopefully, this change will fix this issue.
 3. Tests will run to completion faster and we’ll catch regressions sooner.
 
 The downside: crash stack traces will be like Release build stack traces.  
 But I don’t think we should let this deter us.  It’s not like there’s no 
 stack information.  And just as we do with debugging Release build test 
 failures, we can always do a Debug build locally to do our debugging.
 
 We would like to apply this change to all Debug build and test bots, not 
 just the JSC ones.  Does anyone strongly object to this change?
 
 Thanks.
 
 Cheers,
 Mark
 
 ___
 webkit-dev mailing list
 webkit-dev@lists.webkit.org 
 https://lists.webkit.org/mailman/listinfo/webkit-dev 
 
>>> 
>>> ___
>>> webkit-dev mailing list
>>> webkit-dev@lists.webkit.org 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Mark Lam]

> On Jun 19, 2020, at 9:53 AM, Alexey Proskuryakov  > wrote:
> 
> 
> 
>> 18 июня 2020 г., в 9:30 PM, Saam Barati > > написал(а):
>> 
>> Why are we insisting on doing something on the bots that takes ~10x longer 
>> to run than necessary? I’d rather have that time spent running more tests.
> 
> Replying to this point specifically, I wanted to point out that WebKit tests 
> take 2x longer in debug, not 10x longer. JSC tests take 3.6x longer.

Since I collected real data on this last night on the actual bot that runs the 
JSC stress tests, I’ll share the data here:

Build time
A clean build using buid-jsc for a normal Debug build on bot638 takes about 4.5 
minutes.
A clean build using build-jsc for a --force-opt=O3 Debug build on bot638 takes 
about 6 minutes.

Test run time
Running with a regular Debug build, the test completed in about 4 hours 41 
minutes with 1 timeout.
Running with a --force-opt=O3 Debug build, the test completed in about 39 
minutes with 0 timeouts.

The difference in test run time is 281 minutes vs 29 minutes.  That is a 7.2x 
ratio, not 3.6x.

>> Overall, how we’re doing things now feels like a bad allocation of bot 
>> resources. The differences I see between O3 with no-inlining vs O0 is:
> 
> Last time this was discussed, we talked about -Og, which is specifically 
> designed for the purpose I believe. Where do we stand on understanding and 
> adopting that?

I tried -Og last time after your suggestion, and I remember thinking that the 
perf was not acceptable back then.  I’ll collect the data again and report back 
with real number later today.

Mark

> 
> - Alexey
> 
>> - Some race conditions will behave differently. Race conditions are already 
>> non predictable. I don’t think we’re losing anything here.
>> - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t in 
>> O0, and vice versa. In general, we probably care more about O3 compiler bugs 
>> than O0, since we don’t ship O0, but ship a lot of O3.
>> 
>> (And if we’re going to insist on “I want it to run what I build at my desk”: 
>> I run debug with O3 at my desk, and I can run debug tests in a reasonable 
>> amount of time now.)
>> 
>> In evaluating what’s the better setup, I think it’s helpful to think about 
>> this from the other side. Let’s imagine we had Debug+O3 as our current 
>> setup. And someone proposed to move it to O0 and make our tests take ~10x 
>> longer. I think that’d be a non-starter.
>> 
>> - Saam
>> 
>>> On Jun 17, 2020, at 9:48 PM, Simon Fraser >> > wrote:
>>> 
>>> I also object to losing good stack traces for crashes on Debug bots.
>>> 
>>> Also, I don't think Debug bots should build something different from what I 
>>> build at my desk.
>>> 
>>> Simon
>>> 
 On Jun 17, 2020, at 1:36 PM, Mark Lam >>> > wrote:
 
 Hi folks,
 
 We're planning to switch the JSC EWS bot and build.webkit.org 
  Debug build and test bots to building with the 
 following set first:
 ./Tools/Scripts/set-webkit-configuration --force-opt=O3
 
 This means the Debug builds will be built with optimization level forced 
 to O3.
 
 Why are we doing this?
 1. So that the JSC EWS will start catching ASSERT failures.
 2. JSC stress test Debug bots have been timing out and not running tests 
 at all.  Hopefully, this change will fix this issue.
 3. Tests will run to completion faster and we’ll catch regressions sooner.
 
 The downside: crash stack traces will be like Release build stack traces.  
 But I don’t think we should let this deter us.  It’s not like there’s no 
 stack information.  And just as we do with debugging Release build test 
 failures, we can always do a Debug build locally to do our debugging.
 
 We would like to apply this change to all Debug build and test bots, not 
 just the JSC ones.  Does anyone strongly object to this change?
 
 Thanks.
 
 Cheers,
 Mark
 
 ___
 webkit-dev mailing list
 webkit-dev@lists.webkit.org 
 https://lists.webkit.org/mailman/listinfo/webkit-dev 
 
>>> 
>>> ___
>>> webkit-dev mailing list
>>> webkit-dev@lists.webkit.org 
>>> https://lists.webkit.org/mailman/listinfo/webkit-dev 
>>> 
>> ___
>> webkit-dev mailing list
>> webkit-dev@lists.webkit.org 
>> https://lists.webkit.org/mailman/listinfo/webkit-dev 
>> 
> 
> - Alexey
> 
> 
> ___
> webkit-dev mailing list
> 

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Alexey Proskuryakov]

> 18 июня 2020 г., в 9:30 PM, Saam Barati  написал(а):
> 
> Why are we insisting on doing something on the bots that takes ~10x longer to 
> run than necessary? I’d rather have that time spent running more tests.

Replying to this point specifically, I wanted to point out that WebKit tests 
take 2x longer in debug, not 10x longer. JSC tests take 3.6x longer.

> Overall, how we’re doing things now feels like a bad allocation of bot 
> resources. The differences I see between O3 with no-inlining vs O0 is:

Last time this was discussed, we talked about -Og, which is specifically 
designed for the purpose I believe. Where do we stand on understanding and 
adopting that?

- Alexey

> - Some race conditions will behave differently. Race conditions are already 
> non predictable. I don’t think we’re losing anything here.
> - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t in 
> O0, and vice versa. In general, we probably care more about O3 compiler bugs 
> than O0, since we don’t ship O0, but ship a lot of O3.
> 
> (And if we’re going to insist on “I want it to run what I build at my desk”: 
> I run debug with O3 at my desk, and I can run debug tests in a reasonable 
> amount of time now.)
> 
> In evaluating what’s the better setup, I think it’s helpful to think about 
> this from the other side. Let’s imagine we had Debug+O3 as our current setup. 
> And someone proposed to move it to O0 and make our tests take ~10x longer. I 
> think that’d be a non-starter.
> 
> - Saam
> 
>> On Jun 17, 2020, at 9:48 PM, Simon Fraser  wrote:
>> 
>> I also object to losing good stack traces for crashes on Debug bots.
>> 
>> Also, I don't think Debug bots should build something different from what I 
>> build at my desk.
>> 
>> Simon
>> 
>>> On Jun 17, 2020, at 1:36 PM, Mark Lam >> > wrote:
>>> 
>>> Hi folks,
>>> 
>>> We're planning to switch the JSC EWS bot and build.webkit.org 
>>>  Debug build and test bots to building with the 
>>> following set first:
>>> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
>>> 
>>> This means the Debug builds will be built with optimization level forced to 
>>> O3.
>>> 
>>> Why are we doing this?
>>> 1. So that the JSC EWS will start catching ASSERT failures.
>>> 2. JSC stress test Debug bots have been timing out and not running tests at 
>>> all.  Hopefully, this change will fix this issue.
>>> 3. Tests will run to completion faster and we’ll catch regressions sooner.
>>> 
>>> The downside: crash stack traces will be like Release build stack traces.  
>>> But I don’t think we should let this deter us.  It’s not like there’s no 
>>> stack information.  And just as we do with debugging Release build test 
>>> failures, we can always do a Debug build locally to do our debugging.
>>> 
>>> We would like to apply this change to all Debug build and test bots, not 
>>> just the JSC ones.  Does anyone strongly object to this change?
>>> 
>>> Thanks.
>>> 
>>> Cheers,
>>> Mark
>>> 
>>> ___
>>> webkit-dev mailing list
>>> webkit-dev@lists.webkit.org 
>>> https://lists.webkit.org/mailman/listinfo/webkit-dev
>> 
>> ___
>> webkit-dev mailing list
>> webkit-dev@lists.webkit.org
>> https://lists.webkit.org/mailman/listinfo/webkit-dev
> ___
> webkit-dev mailing list
> webkit-dev@lists.webkit.org
> https://lists.webkit.org/mailman/listinfo/webkit-dev

- Alexey


___
webkit-dev mailing list
webkit-dev@lists.webkit.org
https://lists.webkit.org/mailman/listinfo/webkit-dev

Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Geoffrey Garen]

Can you explain more about what "O3 with no-inlining” is? How does 
--force-opt=O3 avoid inlining? Would this fully resolve Simon concern about 
stack traces, or would something still be different about stack traces?

And again, I think this discussion would get a lot more focused if the change 
could apply only to JSC code, and not also to WTF code.

And again, on the run more tests front, it would be helpful to know whether 
this change was enough to get the stress tests running or not.

Thanks,
Geoff

> On Jun 18, 2020, at 9:30 PM, Saam Barati  wrote:
> 
> Why are we insisting on doing something on the bots that takes ~10x longer to 
> run than necessary? I’d rather have that time spent running more tests.
> 
> Overall, how we’re doing things now feels like a bad allocation of bot 
> resources. The differences I see between O3 with no-inlining vs O0 is:
> - Some race conditions will behave differently. Race conditions are already 
> non predictable. I don’t think we’re losing anything here.
> - O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t in 
> O0, and vice versa. In general, we probably care more about O3 compiler bugs 
> than O0, since we don’t ship O0, but ship a lot of O3.
> 
> (And if we’re going to insist on “I want it to run what I build at my desk”: 
> I run debug with O3 at my desk, and I can run debug tests in a reasonable 
> amount of time now.)
> 
> In evaluating what’s the better setup, I think it’s helpful to think about 
> this from the other side. Let’s imagine we had Debug+O3 as our current setup. 
> And someone proposed to move it to O0 and make our tests take ~10x longer. I 
> think that’d be a non-starter.
> 
> - Saam
> 
>> On Jun 17, 2020, at 9:48 PM, Simon Fraser  wrote:
>> 
>> I also object to losing good stack traces for crashes on Debug bots.
>> 
>> Also, I don't think Debug bots should build something different from what I 
>> build at my desk.
>> 
>> Simon
>> 
>>> On Jun 17, 2020, at 1:36 PM, Mark Lam >> > wrote:
>>> 
>>> Hi folks,
>>> 
>>> We're planning to switch the JSC EWS bot and build.webkit.org 
>>>  Debug build and test bots to building with the 
>>> following set first:
>>> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
>>> 
>>> This means the Debug builds will be built with optimization level forced to 
>>> O3.
>>> 
>>> Why are we doing this?
>>> 1. So that the JSC EWS will start catching ASSERT failures.
>>> 2. JSC stress test Debug bots have been timing out and not running tests at 
>>> all.  Hopefully, this change will fix this issue.
>>> 3. Tests will run to completion faster and we’ll catch regressions sooner.
>>> 
>>> The downside: crash stack traces will be like Release build stack traces.  
>>> But I don’t think we should let this deter us.  It’s not like there’s no 
>>> stack information.  And just as we do with debugging Release build test 
>>> failures, we can always do a Debug build locally to do our debugging.
>>> 
>>> We would like to apply this change to all Debug build and test bots, not 
>>> just the JSC ones.  Does anyone strongly object to this change?
>>> 
>>> Thanks.
>>> 
>>> Cheers,
>>> Mark
>>> 
>>> ___
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>>> webkit-dev@lists.webkit.org 
>>> https://lists.webkit.org/mailman/listinfo/webkit-dev
>> 
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Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Saam Barati]

Why are we insisting on doing something on the bots that takes ~10x longer to 
run than necessary? I’d rather have that time spent running more tests.

Overall, how we’re doing things now feels like a bad allocation of bot 
resources. The differences I see between O3 with no-inlining vs O0 is:
- Some race conditions will behave differently. Race conditions are already non 
predictable. I don’t think we’re losing anything here.
- O0 vs O3 is a different compiler. We may encounter bugs in O3 we don’t in O0, 
and vice versa. In general, we probably care more about O3 compiler bugs than 
O0, since we don’t ship O0, but ship a lot of O3.

(And if we’re going to insist on “I want it to run what I build at my desk”: I 
run debug with O3 at my desk, and I can run debug tests in a reasonable amount 
of time now.)

In evaluating what’s the better setup, I think it’s helpful to think about this 
from the other side. Let’s imagine we had Debug+O3 as our current setup. And 
someone proposed to move it to O0 and make our tests take ~10x longer. I think 
that’d be a non-starter.

- Saam

> On Jun 17, 2020, at 9:48 PM, Simon Fraser  wrote:
> 
> I also object to losing good stack traces for crashes on Debug bots.
> 
> Also, I don't think Debug bots should build something different from what I 
> build at my desk.
> 
> Simon
> 
>> On Jun 17, 2020, at 1:36 PM, Mark Lam  wrote:
>> 
>> Hi folks,
>> 
>> We're planning to switch the JSC EWS bot and build.webkit.org Debug build 
>> and test bots to building with the following set first:
>> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
>> 
>> This means the Debug builds will be built with optimization level forced to 
>> O3.
>> 
>> Why are we doing this?
>> 1. So that the JSC EWS will start catching ASSERT failures.
>> 2. JSC stress test Debug bots have been timing out and not running tests at 
>> all.  Hopefully, this change will fix this issue.
>> 3. Tests will run to completion faster and we’ll catch regressions sooner.
>> 
>> The downside: crash stack traces will be like Release build stack traces.  
>> But I don’t think we should let this deter us.  It’s not like there’s no 
>> stack information.  And just as we do with debugging Release build test 
>> failures, we can always do a Debug build locally to do our debugging.
>> 
>> We would like to apply this change to all Debug build and test bots, not 
>> just the JSC ones.  Does anyone strongly object to this change?
>> 
>> Thanks.
>> 
>> Cheers,
>> Mark
>> 
>> ___
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>> https://lists.webkit.org/mailman/listinfo/webkit-dev
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Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Geoffrey Garen]

Better JSC debugging in exchange for worse debugging in non-JSC code that calls 
through to WTF is not a great tradeoff.

Is there a way to localize this change to only JSC?

Do we know for sure that this change would get stress tests running, or are we 
just guessing? Can we find out? It’s easier to weight a tradeoff between known 
quantities than it is to weigh a tradeoff between hoped-for quantities.

Thanks,
Geoff

> On Jun 18, 2020, at 9:55 AM, Ryan Haddad  wrote:
> 
>> 
>> On Jun 18, 2020, at 9:44 AM, Alex Christensen > > wrote:
>> 
>> It sounds to me like Mark’s suggestion does not lose anything.  It’s just 
>> for JSC “Debug”
> 
> The post-commit JSC bots use the same build products as the other debug 
> testers, so with our current setup it would have to apply to other queues as 
> well.
> 
> Ryan
> 
>> which currently is not running because it’s too slow.  If he called it 
>> “ReleaseWithAssert” it would make it more clear what is going on and we 
>> would all appreciate the additional information those bots provide.
>> 
>>> On Jun 17, 2020, at 9:48 PM, Simon Fraser >> > wrote:
>>> 
>>> I also object to losing good stack traces for crashes on Debug bots.
>>> 
>>> Also, I don't think Debug bots should build something different from what I 
>>> build at my desk.
>>> 
>>> Simon
>>> 
 On Jun 17, 2020, at 1:36 PM, Mark Lam >>> > wrote:
 
 Hi folks,
 
 We're planning to switch the JSC EWS bot and build.webkit.org 
  Debug build and test bots to building with the 
 following set first:
 ./Tools/Scripts/set-webkit-configuration --force-opt=O3
 
 This means the Debug builds will be built with optimization level forced 
 to O3.
 
 Why are we doing this?
 1. So that the JSC EWS will start catching ASSERT failures.
 2. JSC stress test Debug bots have been timing out and not running tests 
 at all.  Hopefully, this change will fix this issue.
 3. Tests will run to completion faster and we’ll catch regressions sooner.
 
 The downside: crash stack traces will be like Release build stack traces.  
 But I don’t think we should let this deter us.  It’s not like there’s no 
 stack information.  And just as we do with debugging Release build test 
 failures, we can always do a Debug build locally to do our debugging.
 
 We would like to apply this change to all Debug build and test bots, not 
 just the JSC ones.  Does anyone strongly object to this change?
 
 Thanks.
 
 Cheers,
 Mark
 
 ___
 webkit-dev mailing list
 webkit-dev@lists.webkit.org 
 https://lists.webkit.org/mailman/listinfo/webkit-dev 
 
>>> 
>>> ___
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Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Ryan Haddad]

> On Jun 18, 2020, at 9:44 AM, Alex Christensen  wrote:
> 
> It sounds to me like Mark’s suggestion does not lose anything.  It’s just for 
> JSC “Debug”

The post-commit JSC bots use the same build products as the other debug 
testers, so with our current setup it would have to apply to other queues as 
well.

Ryan

> which currently is not running because it’s too slow.  If he called it 
> “ReleaseWithAssert” it would make it more clear what is going on and we would 
> all appreciate the additional information those bots provide.
> 
>> On Jun 17, 2020, at 9:48 PM, Simon Fraser > > wrote:
>> 
>> I also object to losing good stack traces for crashes on Debug bots.
>> 
>> Also, I don't think Debug bots should build something different from what I 
>> build at my desk.
>> 
>> Simon
>> 
>>> On Jun 17, 2020, at 1:36 PM, Mark Lam >> > wrote:
>>> 
>>> Hi folks,
>>> 
>>> We're planning to switch the JSC EWS bot and build.webkit.org 
>>>  Debug build and test bots to building with the 
>>> following set first:
>>> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
>>> 
>>> This means the Debug builds will be built with optimization level forced to 
>>> O3.
>>> 
>>> Why are we doing this?
>>> 1. So that the JSC EWS will start catching ASSERT failures.
>>> 2. JSC stress test Debug bots have been timing out and not running tests at 
>>> all.  Hopefully, this change will fix this issue.
>>> 3. Tests will run to completion faster and we’ll catch regressions sooner.
>>> 
>>> The downside: crash stack traces will be like Release build stack traces.  
>>> But I don’t think we should let this deter us.  It’s not like there’s no 
>>> stack information.  And just as we do with debugging Release build test 
>>> failures, we can always do a Debug build locally to do our debugging.
>>> 
>>> We would like to apply this change to all Debug build and test bots, not 
>>> just the JSC ones.  Does anyone strongly object to this change?
>>> 
>>> Thanks.
>>> 
>>> Cheers,
>>> Mark
>>> 
>>> ___
>>> webkit-dev mailing list
>>> webkit-dev@lists.webkit.org 
>>> https://lists.webkit.org/mailman/listinfo/webkit-dev 
>>> 
>> 
>> ___
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>> https://lists.webkit.org/mailman/listinfo/webkit-dev
> 
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Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Alex Christensen]

It sounds to me like Mark’s suggestion does not lose anything.  It’s just for 
JSC “Debug” which currently is not running because it’s too slow.  If he called 
it “ReleaseWithAssert” it would make it more clear what is going on and we 
would all appreciate the additional information those bots provide.

> On Jun 17, 2020, at 9:48 PM, Simon Fraser  wrote:
> 
> I also object to losing good stack traces for crashes on Debug bots.
> 
> Also, I don't think Debug bots should build something different from what I 
> build at my desk.
> 
> Simon
> 
>> On Jun 17, 2020, at 1:36 PM, Mark Lam > > wrote:
>> 
>> Hi folks,
>> 
>> We're planning to switch the JSC EWS bot and build.webkit.org 
>>  Debug build and test bots to building with the 
>> following set first:
>> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
>> 
>> This means the Debug builds will be built with optimization level forced to 
>> O3.
>> 
>> Why are we doing this?
>> 1. So that the JSC EWS will start catching ASSERT failures.
>> 2. JSC stress test Debug bots have been timing out and not running tests at 
>> all.  Hopefully, this change will fix this issue.
>> 3. Tests will run to completion faster and we’ll catch regressions sooner.
>> 
>> The downside: crash stack traces will be like Release build stack traces.  
>> But I don’t think we should let this deter us.  It’s not like there’s no 
>> stack information.  And just as we do with debugging Release build test 
>> failures, we can always do a Debug build locally to do our debugging.
>> 
>> We would like to apply this change to all Debug build and test bots, not 
>> just the JSC ones.  Does anyone strongly object to this change?
>> 
>> Thanks.
>> 
>> Cheers,
>> Mark
>> 
>> ___
>> webkit-dev mailing list
>> webkit-dev@lists.webkit.org 
>> https://lists.webkit.org/mailman/listinfo/webkit-dev
> 
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Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Simon Fraser]

I also object to losing good stack traces for crashes on Debug bots.

Also, I don't think Debug bots should build something different from what I 
build at my desk.

Simon

> On Jun 17, 2020, at 1:36 PM, Mark Lam  wrote:
> 
> Hi folks,
> 
> We're planning to switch the JSC EWS bot and build.webkit.org 
>  Debug build and test bots to building with the 
> following set first:
> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
> 
> This means the Debug builds will be built with optimization level forced to 
> O3.
> 
> Why are we doing this?
> 1. So that the JSC EWS will start catching ASSERT failures.
> 2. JSC stress test Debug bots have been timing out and not running tests at 
> all.  Hopefully, this change will fix this issue.
> 3. Tests will run to completion faster and we’ll catch regressions sooner.
> 
> The downside: crash stack traces will be like Release build stack traces.  
> But I don’t think we should let this deter us.  It’s not like there’s no 
> stack information.  And just as we do with debugging Release build test 
> failures, we can always do a Debug build locally to do our debugging.
> 
> We would like to apply this change to all Debug build and test bots, not just 
> the JSC ones.  Does anyone strongly object to this change?
> 
> Thanks.
> 
> Cheers,
> Mark
> 
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Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Yusuke Suzuki]

In JSC EWS bots. For the other Debug EWS bots, (Like, WebCore Debug builds), I 
have no strong opinion.

-Yusuke

> On Jun 17, 2020, at 6:07 PM, Yusuke Suzuki  wrote:
> 
> For EWS, we are running Release build right now. So in terms of stack traces, 
> nothing is changed.
> 
> -Yusuke
> 
>> On Jun 17, 2020, at 5:21 PM, Alexey Proskuryakov > > wrote:
>> 
>> 
>> I frequently find it critically useful to see stack traces from debug 
>> builds, because of no inlining. So I don't think that we should do this. A 
>> local build does not help when the issue is not readily reproducible.
>> 
>> - Alexey
>> 
>> 
>>> 17 июня 2020 г., в 1:36 PM, Mark Lam >> > написал(а):
>>> 
>>> Hi folks,
>>> 
>>> We're planning to switch the JSC EWS bot and build.webkit.org 
>>>  Debug build and test bots to building with the 
>>> following set first:
>>> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
>>> 
>>> This means the Debug builds will be built with optimization level forced to 
>>> O3.
>>> 
>>> Why are we doing this?
>>> 1. So that the JSC EWS will start catching ASSERT failures.
>>> 2. JSC stress test Debug bots have been timing out and not running tests at 
>>> all.  Hopefully, this change will fix this issue.
>>> 3. Tests will run to completion faster and we’ll catch regressions sooner.
>>> 
>>> The downside: crash stack traces will be like Release build stack traces.  
>>> But I don’t think we should let this deter us.  It’s not like there’s no 
>>> stack information.  And just as we do with debugging Release build test 
>>> failures, we can always do a Debug build locally to do our debugging.
>>> 
>>> We would like to apply this change to all Debug build and test bots, not 
>>> just the JSC ones.  Does anyone strongly object to this change?
>>> 
>>> Thanks.
>>> 
>>> Cheers,
>>> Mark
>>> 
>>> ___
>>> webkit-dev mailing list
>>> webkit-dev@lists.webkit.org 
>>> https://lists.webkit.org/mailman/listinfo/webkit-dev 
>>> 
>> 
>> 
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Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Yusuke Suzuki]

For EWS, we are running Release build right now. So in terms of stack traces, 
nothing is changed.

-Yusuke

> On Jun 17, 2020, at 5:21 PM, Alexey Proskuryakov  wrote:
> 
> 
> I frequently find it critically useful to see stack traces from debug builds, 
> because of no inlining. So I don't think that we should do this. A local 
> build does not help when the issue is not readily reproducible.
> 
> - Alexey
> 
> 
>> 17 июня 2020 г., в 1:36 PM, Mark Lam > > написал(а):
>> 
>> Hi folks,
>> 
>> We're planning to switch the JSC EWS bot and build.webkit.org 
>>  Debug build and test bots to building with the 
>> following set first:
>> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
>> 
>> This means the Debug builds will be built with optimization level forced to 
>> O3.
>> 
>> Why are we doing this?
>> 1. So that the JSC EWS will start catching ASSERT failures.
>> 2. JSC stress test Debug bots have been timing out and not running tests at 
>> all.  Hopefully, this change will fix this issue.
>> 3. Tests will run to completion faster and we’ll catch regressions sooner.
>> 
>> The downside: crash stack traces will be like Release build stack traces.  
>> But I don’t think we should let this deter us.  It’s not like there’s no 
>> stack information.  And just as we do with debugging Release build test 
>> failures, we can always do a Debug build locally to do our debugging.
>> 
>> We would like to apply this change to all Debug build and test bots, not 
>> just the JSC ones.  Does anyone strongly object to this change?
>> 
>> Thanks.
>> 
>> Cheers,
>> Mark
>> 
>> ___
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>> https://lists.webkit.org/mailman/listinfo/webkit-dev
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Re: [webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Alexey Proskuryakov]

I frequently find it critically useful to see stack traces from debug builds, 
because of no inlining. So I don't think that we should do this. A local build 
does not help when the issue is not readily reproducible.

- Alexey


> 17 июня 2020 г., в 1:36 PM, Mark Lam  написал(а):
> 
> Hi folks,
> 
> We're planning to switch the JSC EWS bot and build.webkit.org 
>  Debug build and test bots to building with the 
> following set first:
> ./Tools/Scripts/set-webkit-configuration --force-opt=O3
> 
> This means the Debug builds will be built with optimization level forced to 
> O3.
> 
> Why are we doing this?
> 1. So that the JSC EWS will start catching ASSERT failures.
> 2. JSC stress test Debug bots have been timing out and not running tests at 
> all.  Hopefully, this change will fix this issue.
> 3. Tests will run to completion faster and we’ll catch regressions sooner.
> 
> The downside: crash stack traces will be like Release build stack traces.  
> But I don’t think we should let this deter us.  It’s not like there’s no 
> stack information.  And just as we do with debugging Release build test 
> failures, we can always do a Debug build locally to do our debugging.
> 
> We would like to apply this change to all Debug build and test bots, not just 
> the JSC ones.  Does anyone strongly object to this change?
> 
> Thanks.
> 
> Cheers,
> Mark
> 
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[webkit-dev] Switching open source Debug bots to building and testing with configuration --force-opt=O3

[Mark Lam]

Hi folks,

We're planning to switch the JSC EWS bot and build.webkit.org 
 Debug build and test bots to building with the 
following set first:
./Tools/Scripts/set-webkit-configuration --force-opt=O3

This means the Debug builds will be built with optimization level forced to O3.

Why are we doing this?
1. So that the JSC EWS will start catching ASSERT failures.
2. JSC stress test Debug bots have been timing out and not running tests at 
all.  Hopefully, this change will fix this issue.
3. Tests will run to completion faster and we’ll catch regressions sooner.

The downside: crash stack traces will be like Release build stack traces.  But 
I don’t think we should let this deter us.  It’s not like there’s no stack 
information.  And just as we do with debugging Release build test failures, we 
can always do a Debug build locally to do our debugging.

We would like to apply this change to all Debug build and test bots, not just 
the JSC ones.  Does anyone strongly object to this change?

Thanks.

Cheers,
Mark

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