From: Andrew Morton <akpm@linux-foundation.org>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"hannes@cmpxchg.org" <hannes@cmpxchg.org>,
Michal Hocko <mhocko@suse.cz>, Hugh Dickins <hughd@google.com>,
Ying Han <yinghan@google.com>
Subject: Re: [PATCH 1/4] memcg: simplify page cache charging.
Date: Tue, 20 Dec 2011 13:58:17 -0800 [thread overview]
Message-ID: <20111220135817.5ba7ab05.akpm@linux-foundation.org> (raw)
In-Reply-To: <20111219090122.66024659.kamezawa.hiroyu@jp.fujitsu.com>
On Mon, 19 Dec 2011 09:01:22 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> On Fri, 16 Dec 2011 14:28:14 -0800
> Andrew Morton <akpm@linux-foundation.org> wrote:
>
> > On Wed, 14 Dec 2011 16:49:22 +0900
> > KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> >
> > > Because of commit ef6a3c6311, FUSE uses replace_page_cache() instead
> > > of add_to_page_cache(). Then, mem_cgroup_cache_charge() is not
> > > called against FUSE's pages from splice.
> >
> > Speaking of ef6a3c6311 ("mm: add replace_page_cache_page() function"),
> > may I pathetically remind people that it's rather inefficient?
> >
> > http://lkml.indiana.edu/hypermail/linux/kernel/1109.1/00375.html
> >
>
> IIRC, people says inefficient because it uses memcg codes for page-migration
> for fixing up accounting. Now, We added replace-page-cache for memcg in
> memcg-add-mem_cgroup_replace_page_cache-to-fix-lru-issue.patch
>
> So, I think the problem originally mentioned is fixed.
>
No, the inefficiency in replace_page_cache_page() is still there. Two
identical walks down the radix tree, a pointless decrement then
increment of mapping->nrpages, two writes to page->mapping, an often
pointless decrement then increment of NR_FILE_PAGES, and probably other things.
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next prev parent reply other threads:[~2011-12-20 21:58 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-14 7:47 [PATCH 0/4] memcg: simplify LRU handling KAMEZAWA Hiroyuki
2011-12-14 7:49 ` [PATCH 1/4] memcg: simplify page cache charging KAMEZAWA Hiroyuki
2011-12-16 22:28 ` Andrew Morton
2011-12-19 0:01 ` KAMEZAWA Hiroyuki
2011-12-20 21:58 ` Andrew Morton [this message]
2011-12-21 0:01 ` KAMEZAWA Hiroyuki
2011-12-19 15:04 ` Johannes Weiner
2011-12-20 15:33 ` Michal Hocko
2011-12-14 7:50 ` [PATCH 2/4] memcg: simplify corner case handling of LRU KAMEZAWA Hiroyuki
2011-12-19 15:14 ` Johannes Weiner
2011-12-20 15:05 ` Michal Hocko
2011-12-14 7:51 ` [PATCH 3/4] memcg: clear pc->mem_cgorup if necessary KAMEZAWA Hiroyuki
2011-12-16 22:30 ` Andrew Morton
2011-12-19 15:37 ` Johannes Weiner
2011-12-20 0:35 ` Hiroyuki Kamezawa
2011-12-20 15:56 ` Michal Hocko
2011-12-14 7:52 ` [PATCH 4/4] memcg: simplify LRU handling by new rule KAMEZAWA Hiroyuki
2011-12-19 15:48 ` Johannes Weiner
2011-12-20 16:16 ` Michal Hocko
2011-12-21 0:09 ` KAMEZAWA Hiroyuki
2011-12-21 6:56 ` Michal Hocko
2011-12-19 15:56 ` [PATCH 0/4] memcg: simplify LRU handling Johannes Weiner
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