From: Johannes Weiner <hannes@cmpxchg.org>
To: Tejun Heo <tj@kernel.org>
Cc: akpm@linux-foundation.org, mhocko@kernel.org,
cgroups@vger.kernel.org, linux-mm@kvack.org,
vdavydov@parallels.com, kernel-team@fb.com
Subject: Re: [PATCH v3 2/2] memcg: punt high overage reclaim to return-to-userland path
Date: Tue, 15 Sep 2015 18:33:27 +0200 [thread overview]
Message-ID: <20150915163327.GA13232@cmpxchg.org> (raw)
In-Reply-To: <20150915162253.GI2905@mtj.duckdns.org>
On Tue, Sep 15, 2015 at 12:22:53PM -0400, Tejun Heo wrote:
> Hello,
>
> On Tue, Sep 15, 2015 at 06:12:18PM +0200, Johannes Weiner wrote:
> > But they have been failing indefinitely forever once you hit the hard
> > limit in the past. There was never an async reclaim provision there.
> >
> > I can definitely see that the unconstrained high limit breaching needs
> > to be fixed one way or another, I just don't quite understand why you
> > chose to go for new semantics. Is there a new or a specific usecase
> > you had in mind when you chose deferred reclaim over simply failing?
>
> Hmmm... so if we just fail, it breaks the assumptions that slab/slub
> is making and while they might not fail outright would behave in an
> undesirable way. It's just that we didn't notice that before with
> limit_on_bytes and at least on the v2 interface the distinction
> between high and max makes the problem easy to deal with from high
> enforcement.
Gotcha, it makes sense to address this then. Thanks for clarifying.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
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next prev parent reply other threads:[~2015-09-15 16:33 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-13 18:59 [PATCH 1/2] memcg: flatten task_struct->memcg_oom Tejun Heo
2015-09-13 19:00 ` [PATCH v3 2/2] memcg: punt high overage reclaim to return-to-userland path Tejun Heo
2015-09-15 7:47 ` Johannes Weiner
2015-09-15 15:53 ` Tejun Heo
2015-09-15 16:12 ` Johannes Weiner
2015-09-15 16:22 ` Tejun Heo
2015-09-15 16:33 ` Johannes Weiner [this message]
2015-09-15 7:37 ` [PATCH 1/2] memcg: flatten task_struct->memcg_oom Johannes Weiner
2015-09-20 14:45 ` Sasha Levin
2015-09-21 20:01 ` Tejun Heo
2015-09-30 18:54 ` Tejun Heo
2015-11-25 14:43 ` Peter Zijlstra
2015-11-25 15:02 ` Peter Zijlstra
2015-11-25 15:31 ` Andrey Ryabinin
2015-11-25 17:34 ` Dmitry Vyukov
2015-11-25 17:44 ` Peter Zijlstra
2015-12-11 16:25 ` Tejun Heo
2015-12-15 19:22 ` Peter Zijlstra
2015-12-30 9:23 ` [PATCH v4.4-rc7] sched: isolate task_struct bitfields according to synchronization domains Tejun Heo
2015-12-30 20:10 ` Linus Torvalds
2015-12-30 20:17 ` Linus Torvalds
2015-12-30 20:41 ` Tejun Heo
2015-12-30 20:43 ` Linus Torvalds
2016-01-01 2:56 ` [PATCH v4.4-rc7] sched: move sched lock synchronized bitfields in task_struct into ->atomic_flags Tejun Heo
2016-01-06 13:44 ` Tejun Heo
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