Re: [PATCH] kselftests: cgroup: update kmem test precision tolerance

[Roman Gushchin]

On Fri, Dec 02, 2022 at 09:50:26AM +0100, Michal Hocko wrote:
> OK, so this is a full patch to fix this
> --- 
> From 7f338ed952ba4a100822004bc8399bf720b42899 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@xxxxxxxx>
> Date: Fri, 2 Dec 2022 09:45:29 +0100
> Subject: [PATCH] kselftests: cgroup: update kmem test precision tolerance
> 
> 1813e51eece0 ("memcg: increase MEMCG_CHARGE_BATCH to 64") has changed
> the batch size while this test case has been left behind. This has led
> to a test failure reported by test bot:
> not ok 2 selftests: cgroup: test_kmem # exit=1
> 
> Update the tolerance for the pcp charges to reflect the
> MEMCG_CHARGE_BATCH change to fix this.
> 
> Reported-by: kernel test robot <yujie.liu@xxxxxxxxx>
> Link: https://lore.kernel.org/oe-lkp/202212010958.c1053bd3-yujie.liu@xxxxxxxxx
> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
>  tools/testing/selftests/cgroup/test_kmem.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c
> index 22b31ebb3513..1d073e28254b 100644
> --- a/tools/testing/selftests/cgroup/test_kmem.c
> +++ b/tools/testing/selftests/cgroup/test_kmem.c
> @@ -24,7 +24,7 @@
>   * the maximum discrepancy between charge and vmstat entries is number
>   * of cpus multiplied by 32 pages.
>   */
> -#define MAX_VMSTAT_ERROR (4096 * 32 * get_nprocs())
> +#define MAX_VMSTAT_ERROR (4096 * 64 * get_nprocs())

Hi Michal!

You need to update comments above too (it says 32 pages in a couple of places).
I actually sent the similar patch to Andrew yesterday, but hit reply and missed
adding people to cc.

Please, feel free to send your v2 with comments fixed and my acked-by,
or we can go with my version.

Thanks!

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