Messages in this thread | | | Subject | Re: [LKP] [sched/fair] 070f5e860e: reaim.jobs_per_min -10.5% regression | From | Xing Zhengjun <> | Date | Fri, 19 Jun 2020 13:01:29 +0800 |
| |
On 6/18/2020 8:35 PM, Vincent Guittot wrote: > On Thu, 18 Jun 2020 at 04:45, Xing Zhengjun > <zhengjun.xing@linux.intel.com> wrote: >> >> >> > >>>> >>>> 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 > > There is an improvement but not at the same level as on my setup. > I'm not sure with patch you tested here. Is it the last one that > modify detach_tasks() or the previous one that modify > post_init_entity_util_avg() ? > It is the last one that modify detach_tasks().
> Could you also try the other one ? Both patches were improving results > on y setup but the behavior doesn't seem to be the same on your setup. >
The test result for the other one has been sent in another mail.
> >> 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 >> >> >>>> >>>> > ... >>>>>>> >>>>>>> -- >>>>>>> Zhengjun Xing >>>>> >>>>> -- >>>>> Zhengjun Xing >> >> -- >> Zhengjun Xing
-- Zhengjun Xing
| |