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Message-ID: <28c262360912101712g1c78396die769fe6a5cc3df82@mail.gmail.com>
Date: Fri, 11 Dec 2009 10:12:57 +0900
From: Minchan Kim <minchan.kim@...il.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: "linux-mm@...ck.org" <linux-mm@...ck.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
cl@...ux-foundation.org,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
mingo@...e.hu
Subject: Re: [RFC mm][PATCH 5/5] counting lowmem rss per mm
On Thu, Dec 10, 2009 at 5:01 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@...fujitsu.com> wrote:
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>
> Some case of OOM-Kill is caused by memory shortage in lowmem area. For example,
> NORMAL_ZONE is exhausted on x86-32/HIGHMEM kernel.
>
> Now, oom-killer doesn't have no lowmem usage information of processes and
> selects victim processes based on global memory usage information.
> In bad case, this can cause chains of kills of innocent processes without
> progress, oom-serial-killer.
>
> For making oom-killer lowmem aware, this patch adds counters for accounting
> lowmem usage per process. (patches for oom-killer is not included in this.)
>
> Adding counter is easy but one of concern is the cost for new counter.
>
> Following is the test result of micro-benchmark of parallel page faults.
> Bigger page fault number indicates better scalability.
> (measured under USE_SPLIT_PTLOCKS environemt)
> [Before lowmem counter]
> Performance counter stats for './multi-fault 2' (5 runs):
>
> 46997471 page-faults ( +- 0.720% )
> 1004100076 cache-references ( +- 0.734% )
> 180959964 cache-misses ( +- 0.374% )
> 29263437363580464 bus-cycles ( +- 0.002% )
>
> 60.003315683 seconds time elapsed ( +- 0.004% )
>
> 3.85 miss/faults
> [After lowmem counter]
> Performance counter stats for './multi-fault 2' (5 runs):
>
> 45976947 page-faults ( +- 0.405% )
> 992296954 cache-references ( +- 0.860% )
> 183961537 cache-misses ( +- 0.473% )
> 29261902069414016 bus-cycles ( +- 0.002% )
>
> 60.001403261 seconds time elapsed ( +- 0.000% )
>
> 4.0 miss/faults.
>
> Then, small cost is added. But I think this is within reasonable
> range.
>
> If you have good idea for improve this number, it's welcome.
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Reviewed-by: Minchan Kim <minchan.kim@...il.com>
--
Kind regards,
Minchan Kim
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