From: Hugh Dickins <hughd@google.com>
To: Simon Jeons <simon.jeons@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
dormando <dormando@rydia.net>,
Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>,
Seiji Aguchi <seiji.aguchi@hds.com>,
Satoru Moriya <satoru.moriya@hds.com>,
Randy Dunlap <rdunlap@xenotime.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"lwoodman@redhat.com" <lwoodman@redhat.com>,
Mel Gorman <mel@csn.ul.ie>
Subject: Re: [PATCH] add extra free kbytes tunable
Date: Fri, 1 Mar 2013 19:08:28 -0800 (PST) [thread overview]
Message-ID: <alpine.LNX.2.00.1303011900430.23383@eggly.anvils> (raw)
In-Reply-To: <51316727.1040806@gmail.com>
On Sat, 2 Mar 2013, Simon Jeons wrote:
> On 03/02/2013 09:42 AM, Hugh Dickins wrote:
> > On Sat, 2 Mar 2013, Simon Jeons wrote:
> > > In function __add_to_swap_cache if add to radix tree successfully will
> > > result
> > > in increase NR_FILE_PAGES, why? This is anonymous page instead of file
> > > backed
> > > page.
> > Right, that's hard to understand without historical background.
> >
> > I think the quick answer would be that we used to (and still do) think
> > of file-cache and swap-cache as two halves of page-cache. And then when
>
> shmem page should be treated as file-cache or swap-cache? It is strange since
> it is consist of anonymous pages and these pages establish files.
A shmem page is swap-backed file-cache, and it may get transferred to or
from swap-cache: yes, it's a difficult and confusing case, as I said below.
I would never call it "anonymous", but it is counted in /proc/meminfo's
Active(anon) or Inactive(anon) rather than in (file), because "anon"
there is shorthand for "swap-backed".
> > So you'll find that shmem and swap are counted as file in some places
> > and anon in others, and it's hard to grasp which is where and why,
> > without remembering the history.
Hugh
next prev parent reply other threads:[~2013-03-02 3:09 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-12 2:01 extra free kbytes tunable dormando
2013-02-15 22:21 ` Seiji Aguchi
2013-02-15 22:25 ` Rik van Riel
2013-02-17 23:48 ` [PATCH] add " dormando
2013-02-19 23:29 ` Andrew Morton
2013-02-20 5:19 ` dormando
2013-02-22 17:56 ` Johannes Weiner
2013-02-26 10:47 ` Mel Gorman
2013-02-26 15:13 ` Johannes Weiner
2013-02-26 16:25 ` Mel Gorman
2013-03-01 9:22 ` Simon Jeons
2013-03-01 9:31 ` Simon Jeons
2013-03-01 22:33 ` Hugh Dickins
2013-03-02 0:10 ` Simon Jeons
2013-03-02 1:42 ` Hugh Dickins
2013-03-02 2:42 ` Simon Jeons
2013-03-02 3:08 ` Hugh Dickins [this message]
2013-03-02 4:06 ` Simon Jeons
2013-03-09 1:08 ` Simon Jeons
2013-02-17 23:54 ` dormando
2013-02-15 22:49 ` Satoru Moriya
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