From: Michal Hocko <mhocko@suse.com>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: akpm@linux-foundation.org, hannes@cmpxchg.org,
vdavydov.dev@gmail.com, cgroups@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [Patch v2 3/3] mm/memcg: add next_mz back to soft limit tree if not reclaimed yet
Date: Tue, 15 Mar 2022 09:54:34 +0100 [thread overview]
Message-ID: <YjBUSqh07BIfxbl5@dhcp22.suse.cz> (raw)
In-Reply-To: <20220314230548.wo4colcwqxhhf3mx@master>
On Mon 14-03-22 23:05:48, Wei Yang wrote:
> On Mon, Mar 14, 2022 at 10:41:13AM +0100, Michal Hocko wrote:
> >On Sat 12-03-22 07:16:23, Wei Yang wrote:
> >> When memory reclaim failed for a maximum number of attempts and we bail
> >> out of the reclaim loop, we forgot to put the target mem_cgroup chosen
> >> for next reclaim back to the soft limit tree. This prevented pages in
> >> the mem_cgroup from being reclaimed in the future even though the
> >> mem_cgroup exceeded its soft limit.
> >>
> >> Let's say there are two mem_cgroup and both of them exceed the soft
> >> limit, while the first one is more active then the second. Since we add
> >> a mem_cgroup to soft limit tree every 1024 event, the second one just
> >> get a rare chance to be put on soft limit tree even it exceeds the
> >> limit.
> >
> >yes, 1024 could be just 4MB of memory or 2GB if all the charged pages
> >are THPs. So the excess can build up considerably.
> >
> >> As time goes on, the first mem_cgroup was kept close to its soft limit
> >> due to reclaim activities, while the memory usage of the second
> >> mem_cgroup keeps growing over the soft limit for a long time due to its
> >> relatively rare occurrence.
> >>
> >> This patch adds next_mz back to prevent this sceanrio.
> >>
> >> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> >
> >Even though your changelog is different the change itself is identical to
> >https://lore.kernel.org/linux-mm/8d35206601ccf0e1fe021d24405b2a0c2f4e052f.1613584277.git.tim.c.chen@linux.intel.com/
> >In those cases I would preserve the the original authorship by
> >From: Tim Chen <tim.c.chen@linux.intel.com>
> >and add his s-o-b before yours.
>
> TBH I don't think this is fair.
>
> I didn't see his original change before I sent this patch. This is a
> coincidence we found the same point for improvement.
>
> It hurts me if you want to change authorship. Well, if you really thinks this
> is what it should be, please remove my s-o-b.
OK, fair enough.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2022-03-15 8:54 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-12 7:16 [Patch v2 1/3] mm/memcg: mz already removed from rb_tree in mem_cgroup_largest_soft_limit_node() Wei Yang
2022-03-12 7:16 ` [Patch v2 2/3] mm/memcg: __mem_cgroup_remove_exceeded could handle a !on-tree mz properly Wei Yang
2022-03-14 9:54 ` Michal Hocko
2022-03-14 22:51 ` Wei Yang
2022-03-15 8:52 ` Michal Hocko
2022-03-15 23:54 ` Wei Yang
2022-03-12 7:16 ` [Patch v2 3/3] mm/memcg: add next_mz back to soft limit tree if not reclaimed yet Wei Yang
2022-03-14 9:41 ` Michal Hocko
2022-03-14 23:05 ` Wei Yang
2022-03-15 8:54 ` Michal Hocko [this message]
2022-03-14 9:51 ` [Patch v2 1/3] mm/memcg: mz already removed from rb_tree in mem_cgroup_largest_soft_limit_node() Michal Hocko
2022-03-14 23:21 ` Wei Yang
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