linux-kernel - Re: [LKP] [sched/fair] 6c8116c914: stress-ng.mmapfork.ops_per

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Date:   Tue, 30 Jun 2020 09:43:11 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Xing Zhengjun <zhengjun.xing@...ux.intel.com>
Cc:     Tao Zhou <ouwen210@...mail.com>, linux-kernel@...r.kernel.org,
        Hillf Danton <hdanton@...a.com>,
        kernel test robot <rong.a.chen@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Mel Gorman <mgorman@...e.de>
Subject: Re: [LKP] [sched/fair] 6c8116c914: stress-ng.mmapfork.ops_per_sec
 -38.0% regression

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