Re: [LKP] [sched/fair] 6c8116c914: stress-ng.mmapfork.ops_per_sec -38.0% regression

From: Vincent Guittot
Date: Tue Jun 30 2020 - 03:43:22 EST


Hi Tao,

Le lundi 15 juin 2020 à 16:14:01 (+0800), Xing Zhengjun a écrit :
>
>
> On 6/15/2020 1:18 PM, Tao Zhou wrote:

...

> I apply the patch based on v5.7, the regression still existed.


Could you try the patch below  ? This patch is not a real fix because it impacts performance of others benchmarks but it will at least narrow your problem.


diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9f78eb76f6fb..a4d8614b1854 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8915,9 +8915,9 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
* and consider staying local.
*/

- if ((sd->flags & SD_NUMA) &&
- ((idlest_sgs.avg_load + imbalance) >= local_sgs.avg_load))
- return NULL;
+// if ((sd->flags & SD_NUMA) &&
+// ((idlest_sgs.avg_load + imbalance) >= local_sgs.avg_load))
+// return NULL;

/*
* If the local group is less loaded than the selected

--


> =========================================================================================
> tbox_group/testcase/rootfs/kconfig/compiler/nr_threads/disk/sc_pid_max/testtime/class/cpufreq_governor/ucode:
>
> lkp-bdw-ep6/stress-ng/debian-x86_64-20191114.cgz/x86_64-rhel-7.6/gcc-7/100%/1HDD/4194304/1s/scheduler/performance/0xb000038
>
> commit:
> e94f80f6c49020008e6fa0f3d4b806b8595d17d8
> 6c8116c914b65be5e4d6f66d69c8142eb0648c22
> v5.7
> c7e6d37f60da32f808140b1b7dabcc3cde73c4cc (Tao's patch)
>
> e94f80f6c4902000 6c8116c914b65be5e4d6f66d69c v5.7
> c7e6d37f60da32f808140b1b7da
> ---------------- --------------------------- ---------------------------
> ---------------------------
> %stddev %change %stddev %change %stddev %change
> %stddev
> \ | \ | \
> | \
> 819250 ± 5% -10.1% 736616 ± 8% +41.2% 1156877 ± 3%
> +43.6% 1176246 ± 5% stress-ng.futex.ops
> 818985 ± 5% -10.1% 736460 ± 8% +41.2% 1156215 ± 3%
> +43.6% 1176055 ± 5% stress-ng.futex.ops_per_sec
> 1551 ± 3% -3.4% 1498 ± 5% -4.6% 1480 ± 5%
> -14.3% 1329 ± 11% stress-ng.inotify.ops
> 1547 ± 3% -3.5% 1492 ± 5% -4.8% 1472 ± 5%
> -14.3% 1326 ± 11% stress-ng.inotify.ops_per_sec
> 11292 ± 8% -2.8% 10974 ± 8% -9.4% 10225 ± 6%
> -10.1% 10146 ± 6% stress-ng.kill.ops
> 11317 ± 8% -2.6% 11023 ± 8% -9.1% 10285 ± 5%
> -10.3% 10154 ± 6% stress-ng.kill.ops_per_sec
> 28.20 ± 4% -35.4% 18.22 -33.4% 18.77
> -27.7% 20.40 ± 9% stress-ng.mmapfork.ops_per_sec
> 2999012 ± 21% -10.1% 2696954 ± 22% -88.5% 344447 ± 11%
> -87.8% 364932 stress-ng.tee.ops_per_sec
> 7882 ± 3% -5.4% 7458 ± 4% -2.0% 7724 ± 3%
> -2.2% 7709 ± 4% stress-ng.vforkmany.ops
> 7804 ± 3% -5.2% 7400 ± 4% -2.0% 7647 ± 3%
> -2.1% 7636 ± 4% stress-ng.vforkmany.ops_per_sec
> 46745421 ± 3% -8.1% 42938569 ± 3% -5.2% 44312072 ± 4%
> -2.3% 45648193 stress-ng.yield.ops
> 46734472 ± 3% -8.1% 42926316 ± 3% -5.2% 44290338 ± 4%
> -2.4% 45627571 stress-ng.yield.ops_per_sec
>
>
>

...

> --
> Zhengjun Xing