From: Ying Han <yinghan@google.com>
To: Glauber Costa <glommer@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>,
Johannes Weiner <hannes@cmpxchg.org>, Mel Gorman <mel@csn.ul.ie>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Rik van Riel <riel@redhat.com>, Greg Thelen <gthelen@google.com>,
Christoph Lameter <cl@linux.com>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
linux-mm@kvack.org
Subject: Re: [RFC PATCH 6/6] memcg: shrink slab during memcg reclaim
Date: Thu, 16 Aug 2012 22:51:25 -0700 [thread overview]
Message-ID: <CALWz4ix-fv+m6ohLT8Kn6oJk8duBV4RKU--Gx8GV93vR6Nfq-w@mail.gmail.com> (raw)
In-Reply-To: <502DD54F.3010800@parallels.com>
On Thu, Aug 16, 2012 at 10:23 PM, Glauber Costa <glommer@parallels.com> wrote:
> On 08/17/2012 12:54 AM, Ying Han wrote:
>> This patch makes target reclaim shrinks slabs in addition to userpages.
>>
>> Slab shrinkers determine the amount of pressure to put on slabs based on how
>> many pages are on lru (inversely proportional relationship). Calculate the
>> lru_pages correctly based on memcg lru lists instead of global lru lists.
>>
>> Signed-off-by: Ying Han <yinghan@google.com>
>
> This seems fine from where I stand.
>
> So imagining for an instant we apply this patch, and this patch only.
> The behavior we get is that when memcg gets pressure, it will shrink
> globally, but it will at least shrink anything.
>
> It is needless to say this is not enough. But I wonder if this isn't
> better than no shrinking at all ? Maybe this could be put ontop of the
> slab series and be the temporary default while we sort out the whole
> shrinkers problem?
It is a balance between breaking isolation or risking the memcg to
OOM. Today there is no shrink_slab under target reclaim, and I think
that is
bad after your slab accounting patch. But I do worry about the
isolation bit where you might end up throwing memcg B's pages for
memcg A's pressure. Not only for slab pages but also user pages, like
the example I listed on the first patch.
--Ying
>
>
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prev parent reply other threads:[~2012-08-17 5:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-16 20:54 Ying Han
2012-08-17 5:23 ` Glauber Costa
2012-08-17 5:51 ` Ying Han [this message]
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