From: Fengguang Wu <wfg@mail.ustc.edu.cn>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, Andi Kleen <andi@firstfloor.org>,
Jens Axboe <jens.axboe@oracle.com>,
Oleg Nesterov <oleg@tv-sign.ru>,
Steven Pratt <slpratt@austin.ibm.com>,
Ram Pai <linuxram@us.ibm.com>,
"linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH 1/9] readahead: introduce PG_readahead
Date: Sat, 19 May 2007 20:30:31 +0800 [thread overview]
Message-ID: <379577826.15160@ustc.edu.cn> (raw)
Message-ID: <20070519123031.GA6095@mail.ustc.edu.cn> (raw)
In-Reply-To: <20070518232824.9917d794.akpm@linux-foundation.org>
On Fri, May 18, 2007 at 11:28:24PM -0700, Andrew Morton wrote:
> On Thu, 17 May 2007 06:47:53 +0800 Fengguang Wu <wfg@mail.ustc.edu.cn> wrote:
>
> > Introduce a new page flag: PG_readahead.
>
> Is there any way in which we can avoid adding a new page flag?
>
> We have the advantage that if the kernel very occasionally gets the wrong
> result for PageReadahead(page), nothing particularly bad will happen, so we
> can do racy things.
>
> >From a quick peek, it appears that PG_readahead is only ever set against
> non-uptodate pages. If true we could perhaps exploit that: say,
> PageReadahead(page) == PG_referenced && !PG_uptodate?
PG_uptodate will flip to 1 before the reader touches the page :(
However, it may be possible to share the same bit with PG_reclaim or PG_booked.
Which one would be preferred?
next prev parent reply other threads:[~2007-05-19 12:30 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20070516224752.500812933@mail.ustc.edu.cn>
2007-05-16 22:47 ` [PATCH 0/9] on-demand readahead Fengguang Wu
[not found] ` <20070516224818.384876951@mail.ustc.edu.cn>
2007-05-16 22:47 ` [PATCH 2/9] readahead: add look-ahead support to __do_page_cache_readahead() Fengguang Wu
[not found] ` <20070516224818.544351896@mail.ustc.edu.cn>
2007-05-16 22:47 ` [PATCH 3/9] readahead: MIN_RA_PAGES/MAX_RA_PAGES macros Fengguang Wu
[not found] ` <20070516224818.683288460@mail.ustc.edu.cn>
2007-05-16 22:47 ` [PATCH 4/9] readahead: data structure and routines Fengguang Wu
2007-06-12 3:30 ` Rusty Russell
[not found] ` <20070612120706.GB9624@mail.ustc.edu.cn>
2007-06-12 12:07 ` Fengguang Wu
2007-06-13 0:27 ` Rusty Russell
[not found] ` <20070613030701.GA6494@mail.ustc.edu.cn>
2007-06-13 3:07 ` Fengguang Wu
[not found] ` <20070516224818.841068730@mail.ustc.edu.cn>
2007-05-16 22:47 ` [PATCH 5/9] readahead: on-demand readahead logic Fengguang Wu
2007-05-19 6:23 ` Andrew Morton
[not found] ` <20070519130202.GB6095@mail.ustc.edu.cn>
2007-05-19 13:02 ` Fengguang Wu
2007-06-12 4:36 ` Rusty Russell
[not found] ` <20070612103518.GA9624@mail.ustc.edu.cn>
2007-06-12 10:35 ` Fengguang Wu
2007-06-13 1:40 ` Rusty Russell
[not found] ` <20070613040044.GB6494@mail.ustc.edu.cn>
2007-06-13 4:00 ` Fengguang Wu
2007-06-13 5:51 ` Rusty Russell
[not found] ` <20070613070724.GA6146@mail.ustc.edu.cn>
2007-06-13 7:07 ` Fengguang Wu
[not found] ` <20070516224818.963553696@mail.ustc.edu.cn>
2007-05-16 22:47 ` [PATCH 6/9] readahead: convert filemap invocations Fengguang Wu
[not found] ` <20070516224819.131727893@mail.ustc.edu.cn>
2007-05-16 22:47 ` [PATCH 7/9] readahead: convert splice invocations Fengguang Wu
[not found] ` <20070516224819.420933490@mail.ustc.edu.cn>
2007-05-16 22:48 ` [PATCH 9/9] readahead: remove the old algorithm Fengguang Wu
2007-05-19 12:18 ` Andi Kleen
[not found] ` <20070519131713.GA6510@mail.ustc.edu.cn>
2007-05-19 13:17 ` Fengguang Wu
[not found] ` <20070516224819.281192313@mail.ustc.edu.cn>
2007-05-16 22:48 ` [PATCH 8/9] readahead: convert ext3/ext4 invocations Fengguang Wu
2007-05-19 12:19 ` Andi Kleen
[not found] ` <20070516224818.246719596@mail.ustc.edu.cn>
2007-05-16 22:47 ` [PATCH 1/9] readahead: introduce PG_readahead Fengguang Wu
2007-05-19 6:28 ` Andrew Morton
2007-05-19 11:35 ` Andi Kleen
2007-05-19 15:19 ` Andrew Morton
[not found] ` <20070519123031.GA6095@mail.ustc.edu.cn>
2007-05-19 12:30 ` Fengguang Wu [this message]
2007-05-19 15:25 ` Andrew Morton
[not found] ` <20070520030904.GA9176@mail.ustc.edu.cn>
2007-05-20 3:09 ` Fengguang Wu
2007-05-20 7:10 ` Christoph Lameter
2007-06-12 1:04 ` Rusty Russell
[not found] ` <20070612025201.GA6447@mail.ustc.edu.cn>
2007-06-12 2:52 ` Fengguang Wu
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