Messages in this thread | | | Subject | Re: [LKP] [sched/fair] 070f5e860e: reaim.jobs_per_min -10.5% regression | From | Xing Zhengjun <> | Date | Thu, 18 Jun 2020 10:45:01 +0800 |
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On 6/18/2020 12:25 AM, Vincent Guittot wrote: > Le mercredi 17 juin 2020 à 16:57:25 (+0200), Vincent Guittot a écrit : >> Le mercredi 17 juin 2020 à 08:30:21 (+0800), Xing Zhengjun a écrit : >>> >>> >>> On 6/16/2020 2:54 PM, Vincent Guittot wrote: >>>> >>>> Hi Xing, >>>> >>>> Le mardi 16 juin 2020 à 11:17:16 (+0800), Xing Zhengjun a écrit : >>>>> >>>>> >>>>> On 6/15/2020 4:10 PM, Vincent Guittot wrote: >>>>>> Hi Xing, >>>>>> >>>>>> Le lundi 15 juin 2020 à 15:26:59 (+0800), Xing Zhengjun a écrit : >>>>>>> >>>>>>> >>>>>>> On 6/12/2020 7:06 PM, Hillf Danton wrote: >>>>>>>> >>>>>>>> On Fri, 12 Jun 2020 14:36:49 +0800 Xing Zhengjun wrote: >>>>>> >>>> >>>> ... >>>> > ... >>> >>> I apply the patch based on v5.7, the test result is as the following: >>> >>> ========================================================================================= >>> tbox_group/testcase/rootfs/kconfig/compiler/runtime/nr_task/debug-setup/test/cpufreq_governor/ucode: >>> >>> lkp-ivb-d04/reaim/debian-x86_64-20191114.cgz/x86_64-rhel-7.6/gcc-7/300s/100%/test/five_sec/performance/0x21 >>> >>> commit: >>> 9f68395333ad7f5bfe2f83473fed363d4229f11c >>> 070f5e860ee2bf588c99ef7b4c202451faa48236 >>> v5.7 >>> 63a5d0fbb5ec62f5148c251c01e709b8358cd0ee (the test patch) >>> >>> 9f68395333ad7f5b 070f5e860ee2bf588c99ef7b4c2 v5.7 >>> 63a5d0fbb5ec62f5148c251c01e >>> ---------------- --------------------------- --------------------------- >>> --------------------------- >>> %stddev %change %stddev %change %stddev %change >>> %stddev >>> \ | \ | \ >>> | \ >>> 0.69 -10.3% 0.62 -9.1% 0.62 >>> +1.0% 0.69 reaim.child_systime >>> 0.62 -1.0% 0.61 +0.5% 0.62 >>> -0.1% 0.62 reaim.child_utime >>> 66870 -10.0% 60187 -7.6% 61787 >>> +1.1% 67636 reaim.jobs_per_min >>> 16717 -10.0% 15046 -7.6% 15446 >>> +1.1% 16909 reaim.jobs_per_min_child >> >> OK. So the regression disappears when the conditions on runnable_avg are removed. >> >> In the meantime, I have been able to understand more deeply what was happeningi >> for this bench and how it is impacted by >> commit: 070f5e860ee2 ("sched/fair: Take into account runnable_avg to classify group") >> >> This bench forks a new thread for each and every new step. But a newly forked >> threads start with a load_avg and a runnable_avg set to max whereas the threads >> are running shortly before exiting. This makes the CPU to be set overloaded in >> some case whereas it isn't. >> >> Could you try the patch below ? >> It fixes the problem on my setup (I have finally been able to reproduce the problem) >> >> --- >> kernel/sched/fair.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index 0aeffff62807..b33a4a9e1491 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -807,7 +807,7 @@ void post_init_entity_util_avg(struct task_struct *p) >> } >> } >> >> - sa->runnable_avg = cpu_scale; >> + sa->runnable_avg = sa->util_avg; >> >> if (p->sched_class != &fair_sched_class) { >> /* >> -- >> 2.17.1 >> > > The patch above tries to move back to the group in the same classification as > before but this could harm other benchmarks. > > There is another way to fix this by easing the migration of task in the case > of migrate_util imbalance. > > Could you also try the patch below instead of the one above ? > > --- > kernel/sched/fair.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 0aeffff62807..fcaf66c4d086 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -7753,7 +7753,8 @@ static int detach_tasks(struct lb_env *env) > case migrate_util: > util = task_util_est(p); > > - if (util > env->imbalance) > + if (util/2 > env->imbalance && > + env->sd->nr_balance_failed <= env->sd->cache_nice_tries) > goto next; > > env->imbalance -= util; > -- > 2.17.1 > >
I apply the patch based on v5.7, the test result is as the following:
========================================================================================= tbox_group/testcase/rootfs/kconfig/compiler/runtime/nr_task/debug-setup/test/cpufreq_governor/ucode: lkp-ivb-d04/reaim/debian-x86_64-20191114.cgz/x86_64-rhel-7.6/gcc-7/300s/100%/test/five_sec/performance/0x21
commit: 9f68395333ad7f5bfe2f83473fed363d4229f11c 070f5e860ee2bf588c99ef7b4c202451faa48236 v5.7 69c81543653bf5f2c7105086502889fa019c15cb (the test patch)
9f68395333ad7f5b 070f5e860ee2bf588c99ef7b4c2 v5.7 69c81543653bf5f2c7105086502 ---------------- --------------------------- --------------------------- --------------------------- %stddev %change %stddev %change %stddev %change %stddev \ | \ | \ | \ 0.69 -10.3% 0.62 -9.1% 0.62 -7.6% 0.63 reaim.child_systime 0.62 -1.0% 0.61 +0.5% 0.62 +1.9% 0.63 reaim.child_utime 66870 -10.0% 60187 -7.6% 61787 -5.9% 62947 reaim.jobs_per_min 16717 -10.0% 15046 -7.6% 15446 -5.9% 15736 reaim.jobs_per_min_child 97.84 -1.1% 96.75 -0.4% 97.43 -0.4% 97.47 reaim.jti 72000 -10.8% 64216 -8.3% 66000 -5.7% 67885 reaim.max_jobs_per_min 0.36 +10.6% 0.40 +7.8% 0.39 +6.0% 0.38 reaim.parent_time 1.58 ± 2% +71.0% 2.70 ± 2% +26.9% 2.01 ± 2% +23.6% 1.95 ± 3% reaim.std_dev_percent 0.00 ± 5% +110.4% 0.01 ± 3% +48.8% 0.01 ± 7% +43.2% 0.01 ± 5% reaim.std_dev_time 50800 -2.4% 49600 -1.6% 50000 -0.8% 50400 reaim.workload
>> >> >>> 97.84 -1.1% 96.75 -0.4% 97.43 >>> +0.3% 98.09 reaim.jti >>> 72000 -10.8% 64216 -8.3% 66000 >>> +0.0% 72000 reaim.max_jobs_per_min >>> 0.36 +10.6% 0.40 +7.8% 0.39 >>> -1.1% 0.36 reaim.parent_time >>> 1.58 ± 2% +71.0% 2.70 ± 2% +26.9% 2.01 ± 2% >>> -11.9% 1.39 ± 4% reaim.std_dev_percent >>> 0.00 ± 5% +110.4% 0.01 ± 3% +48.8% 0.01 ± 7% >>> -27.3% 0.00 ± 15% reaim.std_dev_time >>> 50800 -2.4% 49600 -1.6% 50000 >>> +0.0% 50800 reaim.workload >>> >>> >>>>> >>>>> ========================================================================================= >>>>> tbox_group/testcase/rootfs/kconfig/compiler/runtime/nr_task/debug-setup/test/cpufreq_governor/ucode: >>>>> >>>>> lkp-ivb-d04/reaim/debian-x86_64-20191114.cgz/x86_64-rhel-7.6/gcc-7/300s/100%/test/five_sec/performance/0x21 >>>>> >>>>> commit: >>>>> 9f68395333ad7f5bfe2f83473fed363d4229f11c >>>>> 070f5e860ee2bf588c99ef7b4c202451faa48236 >>>>> v5.7 >>>>> 3e1643da53f3fc7414cfa3ad2a16ab2a164b7f4d (the test patch) >>>>> >>>>> 9f68395333ad7f5b 070f5e860ee2bf588c99ef7b4c2 v5.7 >>>>> 3e1643da53f3fc7414cfa3ad2a1 >>>>> ---------------- --------------------------- --------------------------- >>>>> --------------------------- >>>>> %stddev %change %stddev %change %stddev %change >>>>> %stddev >>>>> \ | \ | \ >>>>> | \ >>>>> 0.69 -10.3% 0.62 -9.1% 0.62 >>>>> -7.1% 0.64 reaim.child_systime >>>>> 0.62 -1.0% 0.61 +0.5% 0.62 >>>>> +1.3% 0.63 reaim.child_utime >>>>> 66870 -10.0% 60187 -7.6% 61787 >>>>> -6.1% 62807 reaim.jobs_per_min >>>>> 16717 -10.0% 15046 -7.6% 15446 >>>>> -6.1% 15701 reaim.jobs_per_min_child >>>>> 97.84 -1.1% 96.75 -0.4% 97.43 >>>>> -0.5% 97.34 reaim.jti >>>>> 72000 -10.8% 64216 -8.3% 66000 >>>>> -5.7% 67885 reaim.max_jobs_per_min >>>>> 0.36 +10.6% 0.40 +7.8% 0.39 >>>>> +6.9% 0.38 reaim.parent_time >>>>> 1.58 ± 2% +71.0% 2.70 ± 2% +26.9% 2.01 ± 2% >>>>> +32.5% 2.09 ± 6% reaim.std_dev_percent >>>>> 0.00 ± 5% +110.4% 0.01 ± 3% +48.8% 0.01 ± 7% >>>>> +61.7% 0.01 ± 8% reaim.std_dev_time >>>>> 50800 -2.4% 49600 -1.6% 50000 >>>>> -1.3% 50133 reaim.workload >>>>> >>>>> >>>>>>> >>>>>>> ========================================================================================= >>>>>>> tbox_group/testcase/rootfs/kconfig/compiler/runtime/nr_task/debug-setup/test/cpufreq_governor/ucode: >>>>>>> >>>>>>> lkp-ivb-d04/reaim/debian-x86_64-20191114.cgz/x86_64-rhel-7.6/gcc-7/300s/100%/test/five_sec/performance/0x21 >>>>>>> >>>>>>> commit: >>>>>>> 9f68395333ad7f5bfe2f83473fed363d4229f11c >>>>>>> 070f5e860ee2bf588c99ef7b4c202451faa48236 >>>>>>> v5.7 >>>>>>> 6b33257768b8dd3982054885ea310871be2cfe0b (Hillf's patch) >>>>>>> >>>>>>> 9f68395333ad7f5b 070f5e860ee2bf588c99ef7b4c2 v5.7 >>>>>>> 6b33257768b8dd3982054885ea3 >>>>>>> ---------------- --------------------------- --------------------------- >>>>>>> --------------------------- >>>>>>> %stddev %change %stddev %change %stddev %change >>>>>>> %stddev >>>>>>> \ | \ | \ >>>>>>> | \ >>>>>>> 0.69 -10.3% 0.62 -9.1% 0.62 >>>>>>> -10.1% 0.62 reaim.child_systime >>>>>>> 0.62 -1.0% 0.61 +0.5% 0.62 >>>>>>> +0.3% 0.62 reaim.child_utime >>>>>>> 66870 -10.0% 60187 -7.6% 61787 >>>>>>> -8.3% 61305 reaim.jobs_per_min >>>>>>> 16717 -10.0% 15046 -7.6% 15446 >>>>>>> -8.3% 15326 reaim.jobs_per_min_child >>>>>>> 97.84 -1.1% 96.75 -0.4% 97.43 >>>>>>> -0.5% 97.37 reaim.jti >>>>>>> 72000 -10.8% 64216 -8.3% 66000 >>>>>>> -8.3% 66000 reaim.max_jobs_per_min >>>>>>> 0.36 +10.6% 0.40 +7.8% 0.39 >>>>>>> +9.4% 0.39 reaim.parent_time >>>>>>> 1.58 ± 2% +71.0% 2.70 ± 2% +26.9% 2.01 ± 2% >>>>>>> +33.2% 2.11 reaim.std_dev_percent >>>>>>> 0.00 ± 5% +110.4% 0.01 ± 3% +48.8% 0.01 ± 7% >>>>>>> +65.3% 0.01 ± 3% reaim.std_dev_time >>>>>>> 50800 -2.4% 49600 -1.6% 50000 >>>>>>> -1.8% 49866 reaim.workload >>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Zhengjun Xing >>>>> >>>>> -- >>>>> Zhengjun Xing >>> >>> -- >>> Zhengjun Xing
-- Zhengjun Xing
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