On Fri, Jun 03, 2016 at 06:21:09PM -0400, Johannes Weiner wrote:
>On Thu, Jun 02, 2016 at 12:07:06PM -0400, Johannes Weiner wrote:
>> Hi,
>>
>> On Thu, Jun 02, 2016 at 02:45:07PM +0800, kernel test robot wrote:
>> > FYI, we noticed pixz.throughput -9.1% regression due to commit:
>> >
>> > commit 795ae7a0de6b834a0cc202aa55c190ef81496665 ("mm: scale kswapd
>> > watermarks in proportion to memory")
>> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>> >
>> > in testcase: pixz
>> > on test machine: ivb43: 48 threads Ivytown Ivy Bridge-EP with 64G memory
>> > with following parameters: cpufreq_governor=performance/nr_threads=100%
>>
>> Xiaolong, thanks for the report.
>>
>> It looks like the regression stems from a change in NUMA placement:
>
>Scratch that, I was misreading the test results. It's just fewer
>allocations in general that happen during the fixed testing time.
>
>I'm stumped by this report. All this patch does other than affect page
>reclaim (which is not involved here) is increase the size of the round
>robin batches in the fair zone allocator. That should *reduce* work in
>the page allocator, if anything.
>
>But I also keep failing to reproduce this - having tried it on the
>third machine now - neither pixz nor will-it-scale/page_fault1 give me
>that -8-9% regression:
>
>4.5.0-02574-g3ed3a4f:
>PIXZ-good.log:throughput: 39908733.604941994
>PIXZ-good.log:throughput: 37067947.25049969
>PIXZ-good.log:throughput: 38604938.39131216
>
>4.5.0-02575-g795ae7a:
> PIXZ-bad.log:throughput: 39489120.87179377
> PIXZ-bad.log:throughput: 39307299.288432725
> PIXZ-bad.log:throughput: 38795994.3329781
>
>Is this reliably reproducible with 3ed3a4f vs 795ae7a?
Yes, it can be stably reproduced in LKP environment, I've run 3ed3a4f0ddffece9
for 4 times, and 795ae7a0de6b834a0cc202aa55 for 7 times.
3ed3a4f0ddffece9 795ae7a0de6b834a0cc202aa55
---------------- --------------------------
fail:runs %reproduction fail:runs
| | |
:4 50% 2:7
kmsg.Spurious_LAPIC_timer_interrupt_on_cpu
%stddev %change %stddev
\ | \
78505362 ± 0% -9.2% 71298182 ± 0% pixz.throughput
>
>Could I ask you to retry the test with Linus's current head as well as
>with 795ae7a reverted on top of it? (It's a clean revert.)
>
Sure, I have queued the test tasks for them, will update the comparison
once I get the results.
Thanks,
Xiaolong
>Thanks
