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Date: Fri, 30 Jun 2023 10:28:14 +0200
From: Vincent Guittot <vincent.guittot@...aro.org>
To: Saeed Mirzamohammadi <saeed.mirzamohammadi@...cle.com>
Cc: Chen Yu <yu.c.chen@...el.com>, Ingo Molnar <mingo@...hat.com>,
"peterz@...radead.org" <peterz@...radead.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"zhangqiao22@...wei.com" <zhangqiao22@...wei.com>
Subject: Re: Reporting a performance regression in sched/fair on Unixbench
Shell Scripts with commit a53ce18cacb4
On Fri, 30 Jun 2023 at 00:20, Saeed Mirzamohammadi
<saeed.mirzamohammadi@...cle.com> wrote:
>
>
>
> > On Jun 21, 2023, at 9:41 AM, Saeed Mirzamohammadi <saeed.mirzamohammadi@...cle.com> wrote:
> >
> > Hi Chen, Vincent,
> >
> >> On Jun 13, 2023, at 11:37 PM, Chen Yu <yu.c.chen@...el.com> wrote:
> >>
> >> On 2023-06-13 at 19:35:55 +0000, Saeed Mirzamohammadi wrote:
> >>> Hi Vincent,
> >>>
> >>>> On Jun 9, 2023, at 9:52 AM, Vincent Guittot <vincent.guittot@...aro.org> wrote:
> >>>>
> >>>> Hi Saeed,
> >>>>
> >>>> On Fri, 9 Jun 2023 at 00:48, Saeed Mirzamohammadi
> >>>> <saeed.mirzamohammadi@...cle.com> wrote:
> >>>>>
> >>>>> Hi all,
> >>>>>
> >>>>> I’m reporting a regression of up to 8% with Unixbench Shell Scripts benchmarks after the following commit:
> >>>>>
> >>>>> Commit Data:
> >>>>> commit-id : a53ce18cacb477dd0513c607f187d16f0fa96f71
> >>>>> subject : sched/fair: Sanitize vruntime of entity being migrated
> >>>>> author : vincent.guittot@...aro.org
> >>>>> author date : 2023-03-17 16:08:10
> >>>>>
> >>>>>
> >>>>> We have observed this on our v5.4 and v4.14 kernel and not yet tested 5.15 but I expect the same.
> >>>>
> >>>> It would be good to confirm that the regression is present on v6.3
> >>>> where the patch has been merged originally. It can be that there is
> >>>> hidden dependency with other patches introduced since v5.4
> >>>
> >>> Regression is present on v6.3 as well, examples:
> >>> ub_gcc_224copies_Shell_Scripts_8_concurrent: ~6%
> >>> ub_gcc_224copies_Shell_Scripts_16_concurrent: ~8%
> >>> ub_gcc_448copies_Shell_Scripts_1_concurrent: ~2%
> >
> > Apologize for the confusion, I should correct the v6.3 upstream result above. v6.3 doesn’t have any regression.
> > v6.3.y -> no regression
> > v5.15.y -> no regression
> > v5.4.y -> 5-8% regression.
>
> A gentle reminder if there is any recommendation for v5.4.y and v4.14.y regression. Thanks!
I tried to find why the regression happens only for v5.4.y (or lower)
and not for v5.15.y (or above) but I haven't been able to find any
possible reason in the code.
Regarding the 2 commits below, they must come together so we can't
simply revert 1 and not the other.
commit 829c1651e9c4 sched/fair: sanitize vruntime of entity being placed
commit a53ce18cacb4 sched/fair: Sanitize vruntime of entity being migrated
entity_is_long_sleeper() should never return true in your case. Could
you try to check that it's the case for you ?
>
> >
> >
> >>>>
> >>>>
> >>>>>
> >>>>> ub_gcc_1copy_Shell_Scripts_1_concurrent : -0.01%
> >>>>> ub_gcc_1copy_Shell_Scripts_8_concurrent : -0.1%
> >>>>> ub_gcc_1copy_Shell_Scripts_16_concurrent : -0.12%%
> >>>>> ub_gcc_56copies_Shell_Scripts_1_concurrent : -2.29%%
> >>>>> ub_gcc_56copies_Shell_Scripts_8_concurrent : -4.22%
> >>>>> ub_gcc_56copies_Shell_Scripts_16_concurrent : -4.23%
> >>>>> ub_gcc_224copies_Shell_Scripts_1_concurrent : -5.54%
> >>>>> ub_gcc_224copies_Shell_Scripts_8_concurrent : -8%
> >>>>> ub_gcc_224copies_Shell_Scripts_16_concurrent : -7.05%
> >>>>> ub_gcc_448copies_Shell_Scripts_1_concurrent : -6.4%
> >>>>> ub_gcc_448copies_Shell_Scripts_8_concurrent : -8.35%
> >>>>> ub_gcc_448copies_Shell_Scripts_16_concurrent : -7.09%
> >>>>>
> >>>>> Link to unixbench:
> >>>>> github.com/kdlucas/byte-unixbench
> >>>>
> >>>> I tried to reproduce the problem with v6.3 on my system but I don't
> >>>> see any difference with or without the patch
> >>>>
> >>>> Do you have more details on your setup ? number of cpu and topology ?
> >>>>
> >>> model name : Intel(R) Xeon(R) CPU E5-2690 v4 @ 2.60GHz
> >>>
> >>> Topology:
> >>> node 0 1
> >>> 0: 10 21
> >>> 1: 21 10
> >>>
> >>> Architecture: x86_64
> >>> CPU op-mode(s): 32-bit, 64-bit
> >>> CPU(s): 56
> >>> On-line CPU(s) list: 0-55
> >>> Thread(s) per core: 2
> >>> Core(s) per socket: 14
> >>> Socket(s): 2
> >>> NUMA node(s): 2
> >>>
> >> Tested on a similar platform E5-2697 v2 @ 2.70GHz which has 2 nodes,
> >> 24 cores/48 CPUs in total, however I could not reproduce the issue.
> >> Since the regression was reported mainly against 224 and 448 copies case
> >> on your platform, I tested unixbench shell1 with 4 x 48 = 192 copies.
> >>
> >>
> >> a53ce18cacb477dd 213acadd21a080fc8cda8eebe6d
> >> ---------------- ---------------------------
> >> %stddev %change %stddev
> >> \ | \
> >> 21304 +0.5% 21420 unixbench.score
> >> 632.43 +0.0% 632.44 unixbench.time.elapsed_time
> >> 632.43 +0.0% 632.44 unixbench.time.elapsed_time.max
> >> 11837046 -4.7% 11277727 unixbench.time.involuntary_context_switches
> >> 864713 +0.1% 865914 unixbench.time.major_page_faults
> >> 9600 +4.0% 9984 unixbench.time.maximum_resident_set_size
> >> 8.433e+08 +0.6% 8.48e+08 unixbench.time.minor_page_faults
> >> 4096 +0.0% 4096 unixbench.time.page_size
> >> 3741 +1.1% 3783 unixbench.time.percent_of_cpu_this_job_got
> >> 18341 +1.3% 18572 unixbench.time.system_time
> >> 5323 +0.6% 5353 unixbench.time.user_time
> >> 78197044 -3.1% 75791701 unixbench.time.voluntary_context_switches
> >> 57178573 +0.4% 57399061 unixbench.workload
> >>
> >> There is no much difference with a53ce18cacb477dd applied or not.
> >>
> >>
> >>
> >>
> >>
> >> a2e90611b9f425ad 829c1651e9c4a6f78398d3e6765
> >> ---------------- ---------------------------
> >> %stddev %change %stddev
> >> \ | \
> >> 19985 +8.6% 21697 unixbench.score
> >> 632.64 -0.0% 632.53 unixbench.time.elapsed_time
> >> 632.64 -0.0% 632.53 unixbench.time.elapsed_time.max
> >> 11453985 +3.7% 11880259 unixbench.time.involuntary_context_switches
> >> 818996 +3.1% 844681 unixbench.time.major_page_faults
> >> 9600 +0.0% 9600 unixbench.time.maximum_resident_set_size
> >> 7.911e+08 +8.4% 8.575e+08 unixbench.time.minor_page_faults
> >> 4096 +0.0% 4096 unixbench.time.page_size
> >> 3767 -0.4% 3752 unixbench.time.percent_of_cpu_this_job_got
> >> 18873 -2.4% 18423 unixbench.time.system_time
> >> 4960 +7.1% 5313 unixbench.time.user_time
> >> 75436000 +10.8% 83581483 unixbench.time.voluntary_context_switches
> >> 53553404 +8.7% 58235303 unixbench.workload
> >>
> >> Previously with 829c1651e9c4a6f introduced, there is 8.6% improvement. And this improvement
> >> remains with a53ce18cacb477dd applied.
> >>
> >> Can you send the full test script so I can have a try locally?
> >
> > Thanks for testing this. For v5.4.y kernel (not for v6.3.y or v5.15.y), there is an 8% regression with the following test: ub_gcc_448copies_Shell_Scripts_8_concurrent
> > And that’s ’shell8’ with ‘-c 448’ copies passed as argument.
> >
> > Thanks,
> > Saeed
> >
> >>
> >> thanks,
> >> Chenyu
>
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