2009/6/9 Tobias Käs <[email protected]>:
> Sounds like we are talking about different scripts. The only one I could
The correct string-add.js isn't in the repo:
// Completely artificial String addition benchmark.
function benchmark() {
var x = "";
for (var i = 0; i < 1000000; i++) {
x = x + "x";
}
x.indexOf('x'); // Flatten string.
}
var elapsed = 0;
var start = new Date();
for (var n = 0; elapsed < 2000; n++) {
benchmark();
elapsed = new Date() - start;
}
print('Time (string-add): ' + Math.floor(1000 * elapsed/n) + ' us.');
> find was test/mjsunit/string-add.js ... which doesn't seem to do any timing
> by itself, just doing assertion checks - and the assert functions are
> defined in mjsunit.js which is why I'm getting an exception if I don't
> execute it before string-add.js
>
> Since I couldn't get any timing I added some myself in the main entry point,
> but that obviously includes startup/shutdown. That's also why I noticed
> shell calls V8::Dispose but d8 doesn't (at least not anywhere near the main
> entrypoint).
>
> I was trying to reproduce it on windows but I couldn't get any sensible
> values, everything drowned in the noise of startup/shutdown and was pretty
> much random. I could also test on several debian linux boxes, but it
> probably only makes sense if I find the correct script to run. Sorry I
> couldn't be of more help, I'm still trying to find my way around in the
> project and sometimes make stupid mistakes.
>
> 2009/6/8 Anton Muhin <[email protected]>
>>
>> Good day, Tobias!
>>
>> On Sat, Jun 6, 2009 at 11:34 AM, Tobias Käs<[email protected]>
>> wrote:
>> > I noticed that shell does a V8::Dispose and d8 doesn't do this ... is
>> > that included in your timing? Also, unless you are averaging multiple
>> > runs, the total time is so small that it may be just some startup/
>> > shutdown noise?
>>
>> I did more runs and the pattern is really stable: d8 shows almost
>> identical times every time and shell shows this 1.5 slowdown most of
>> time, but not always.
>>
>> May you elaborate a bit on V8::Dispose? Timing is just as in
>> string-add.js, so that doesn't include startup/shutdown stuff.
>>
>> >
>> > PS: Are you using modified code or is this platform-specific
>> > behaviour? I had to add mjsunit.js to the command line, otherwise I'm
>> > getting an exception. Plus I don't get any timings out of d8/shell.
>>
>> Hmm, that was on Linux and ran just fine. What's the platform you
>> experienced problems on?
>>
>> Thanks a lot and yours,
>> anton.
>>
>> >
>> > On 5 Jun., 17:09, Anton Muhin <[email protected]> wrote:
>> >> Dear v8ers,
>> >>
>> >> Erik pointed out that my r2110 dramatically reduced performance of
>> >> several benchmarks, including string-add. I compiled two versions,
>> >> with and without 2110 and they ran fine on my box. Erik suggested to
>> >> run them on newt.aar and here began the mistery: unless I misbuilt the
>> >> stuff results look:
>> >>
>> >> ant...@newt:/home/erikcorry/b$ ~/d8-2110 string-add.js && ~/d8-2111
>> >> string-add.js
>> >> Time (string-add): 301000 us.
>> >> Time (string-add): 301428 us.
>> >> ant...@newt:/home/erikcorry/b$ ~/d8-2110 string-add.js && ~/d8-2111
>> >> string-add.js
>> >> Time (string-add): 301857 us.
>> >> Time (string-add): 302857 us.
>> >> ant...@newt:/home/erikcorry/b$ ~/d8-2110 string-add.js && ~/d8-2111
>> >> string-add.js
>> >> Time (string-add): 309714 us.
>> >> Time (string-add): 306142 us.
>> >> ant...@newt:/home/erikcorry/b$ ~/d8-2110 string-add.js && ~/d8-2111
>> >> string-add.js
>> >> Time (string-add): 300714 us.
>> >> Time (string-add): 301857 us.
>> >> ant...@newt:/home/erikcorry/b$ ~/d8-2110 string-add.js && ~/d8-2111
>> >> string-add.js
>> >> Time (string-add): 301571 us.
>> >> Time (string-add): 300714 us.
>> >> ant...@newt:/home/erikcorry/b$ ~/d8-2110 string-add.js && ~/d8-2111
>> >> string-add.js
>> >> Time (string-add): 302571 us.
>> >> Time (string-add): 301428 us.
>> >> ant...@newt:/home/erikcorry/b$ ~/shell-2110 string-add.js &&
>> >> ~/shell-2111 string-add.js
>> >> Time (string-add): 446800 us.
>> >> Time (string-add): 302142 us.
>> >> ant...@newt:/home/erikcorry/b$ ~/shell-2110 string-add.js &&
>> >> ~/shell-2111 string-add.js
>> >> Time (string-add): 306857 us.
>> >> Time (string-add): 309857 us.
>> >> ant...@newt:/home/erikcorry/b$ ~/shell-2110 string-add.js &&
>> >> ~/shell-2111 string-add.js
>> >> Time (string-add): 449400 us.
>> >> Time (string-add): 303285 us.
>> >> ant...@newt:/home/erikcorry/b$ ~/shell-2110 string-add.js &&
>> >> ~/shell-2111 string-add.js
>> >> Time (string-add): 436800 us.
>> >> Time (string-add): 306428 us.
>> >> ant...@newt:/home/erikcorry/b$ ~/shell-2110 string-add.js &&
>> >> ~/shell-2111 string-add.js
>> >> Time (string-add): 432200 us.
>> >> Time (string-add): 304000 us.
>> >>
>> >> (r2111 rolls 2110 back, d8 and shell are corresponding binaries, built
>> >> as scons -j4 sample=shell and scons -j4 d8 correspondingly).
>> >>
>> >> Fun facts: d8 for both 2110 and 2111 runs in same time, shell for 2110
>> >> usually runs 1.5 (!) longer, but sometimes (~10-20% of the cases)
>> >> identically to 2111.
>> >>
>> >> Does anyone have any idea what might have happened? Erik suggested
>> >> that things are linked somewhat differently.
>> >>
>> >> Change itself looks quite plain and it's not obvious how that can
>> >> introduce any regression:
>> >>
>> >> The only thing I can immediately see is expensive IsJSGlobalProxy, but
>> >> why this is that instable, that'd be odd if more invocations to
>> >> IsJSGlobalProxy would lead to more GCing.
>> >>
>> >> Any ideas are most appreciated.
>> >>
>> >> tia and yours,
>> >> anton.
>> >
>
>
--
Erik Corry, Software Engineer
Google Denmark ApS. CVR nr. 28 86 69 84
c/o Philip & Partners, 7 Vognmagergade, P.O. Box 2227, DK-1018
Copenhagen K, Denmark.
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