From: Ying Han <yinghan@google.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>, Mel Gorman <mel@csn.ul.ie>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Rik van Riel <riel@redhat.com>, Hillf Danton <dhillf@gmail.com>,
Hugh Dickins <hughd@google.com>,
Dan Magenheimer <dan.magenheimer@oracle.com>,
linux-mm@kvack.org
Subject: Re: [PATCH V2 5/5] memcg: change the target nr_to_reclaim for each memcg under kswapd
Date: Wed, 11 Apr 2012 21:06:27 -0700 [thread overview]
Message-ID: <CALWz4ixnQ=XWUmPEqjEnGYrO6p+pU=VEGjJSEr22gfnmNPjrmg@mail.gmail.com> (raw)
In-Reply-To: <20120411235638.GA1787@cmpxchg.org>
On Wed, Apr 11, 2012 at 4:56 PM, Johannes Weiner <hannes@cmpxchg.org> wrote:
> On Wed, Apr 11, 2012 at 03:00:27PM -0700, Ying Han wrote:
>> Under global background reclaim, the sc->nr_to_reclaim is set to
>> ULONG_MAX. Now we are iterating all memcgs under the zone and we
>> shouldn't pass the pressure from kswapd for each memcg.
>>
>> After all, the balance_pgdat() breaks after reclaiming SWAP_CLUSTER_MAX
>> pages to prevent building up reclaim priorities.
>
> shrink_mem_cgroup_zone() bails out of a zone, balance_pgdat() bails
> out of a priority loop, there is quite a difference.
>
> After this patch, kswapd no longer puts equal pressure on all zones in
> the zonelist, which was a key reason why we could justify bailing
> early out of individual zones in direct reclaim: kswapd will restore
> fairness.
Guess I see your point here.
My intention is to prevent over-reclaim memcgs per-zone by having
nr_to_reclaim to ULONG_MAX. Now, we scan each memcg based on
get_scan_count() without bailout, do you see a problem w/o this patch?
--Ying
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next prev parent reply other threads:[~2012-04-12 4:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-11 22:00 Ying Han
2012-04-11 23:56 ` Johannes Weiner
2012-04-12 4:06 ` Ying Han [this message]
2012-04-12 14:24 ` Johannes Weiner
2012-04-12 16:45 ` Ying Han
2012-04-12 17:44 ` Johannes Weiner
2012-04-12 17:58 ` Ying Han
2012-04-15 1:57 ` Hillf Danton
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