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Date:   Mon, 5 Dec 2022 08:33:09 +0100
From:   Michal Hocko <mhocko@suse.com>
To:     Roman Gushchin <roman.gushchin@linux.dev>
Cc:     kernel test robot <yujie.liu@intel.com>,
        Shakeel Butt <shakeelb@google.com>, oe-lkp@lists.linux.dev,
        lkp@intel.com, Andrew Morton <akpm@linux-foundation.org>,
        kernel test robot <oliver.sang@intel.com>,
        Soheil Hassas Yeganeh <soheil@google.com>,
        Feng Tang <feng.tang@intel.com>,
        Muchun Song <songmuchun@bytedance.com>,
        Eric Dumazet <edumazet@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kselftests: cgroup: update kmem test precision tolerance
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On Fri 02-12-22 09:16:17, Roman Gushchin wrote:
> 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@suse.com>
> > 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@intel.com>
> > Link: https://lore.kernel.org/oe-lkp/202212010958.c1053bd3-yujie.liu@intel.com
> > Signed-off-by: Michal Hocko <mhocko@suse.com>
> > ---
> >  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.

It seems Andrew has already done all the fixups. Thanks both to you and
Andrew!
-- 
Michal Hocko
SUSE Labs