From: Rik van Riel <riel@redhat.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jens Axboe <jens.axboe@oracle.com>, Nick Piggin <npiggin@suse.de>,
Andi Kleen <andi@firstfloor.org>,
Steven Whitehouse <swhiteho@redhat.com>,
Chris Mason <chris.mason@oracle.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Clemens Ladisch <clemens@ladisch.de>,
Olivier Galibert <galibert@pobox.com>,
Vivek Goyal <vgoyal@redhat.com>,
Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>,
Matt Mackall <mpm@selenic.com>,
Linux Memory Management List <linux-mm@kvack.org>,
linux-fsdevel@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 06/15] readahead: replace ra->mmap_miss with ra->ra_flags
Date: Thu, 25 Feb 2010 10:52:28 -0500 [thread overview]
Message-ID: <4B869CBC.5070501@redhat.com> (raw)
In-Reply-To: <20100224031054.449606633@intel.com>
On 02/23/2010 10:10 PM, Wu Fengguang wrote:
> Introduce a readahead flags field and embed the existing mmap_miss in it
> (mainly to save space).
>
> It also changes the mmap_miss upper bound from LONG_MAX to 4096.
> This is to help adapt properly for changing mmap access patterns.
>
> It will be possible to lose the flags in race conditions, however the
> impact should be limited. For the race to happen, there must be two
> threads sharing the same file descriptor to be in page fault or
> readahead at the same time.
>
> Note that it has always been racy for "page faults" at the same time.
>
> And if ever the race happen, we'll lose one mmap_miss++ or mmap_miss--.
> Which may change some concrete readahead behavior, but won't really
> impact overall I/O performance.
>
> CC: Nick Piggin<npiggin@suse.de>
> CC: Andi Kleen<andi@firstfloor.org>
> CC: Steven Whitehouse<swhiteho@redhat.com>
> Signed-off-by: Wu Fengguang<fengguang.wu@intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
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next prev parent reply other threads:[~2010-02-25 15:52 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-24 3:10 [PATCH 00/15] 512K readahead size with thrashing safe readahead v2 Wu Fengguang
2010-02-24 3:10 ` [PATCH 01/15] readahead: limit readahead size for small devices Wu Fengguang
2010-02-25 3:11 ` Rik van Riel
2010-02-24 3:10 ` [PATCH 02/15] readahead: retain inactive lru pages to be accessed soon Wu Fengguang
2010-02-25 3:17 ` Rik van Riel
2010-02-25 12:27 ` Wu Fengguang
2010-02-24 3:10 ` [PATCH 03/15] readahead: bump up the default readahead size Wu Fengguang
2010-02-25 4:02 ` Rik van Riel
2010-02-24 3:10 ` [PATCH 04/15] readahead: make default readahead size a kernel parameter Wu Fengguang
2010-02-25 14:59 ` Rik van Riel
2010-02-24 3:10 ` [PATCH 05/15] readahead: limit readahead size for small memory systems Wu Fengguang
2010-02-25 15:00 ` Rik van Riel
2010-02-25 15:25 ` Christian Ehrhardt
2010-02-26 2:29 ` Wu Fengguang
2010-02-26 2:48 ` [PATCH] readahead: add notes on readahead size Wu Fengguang
2010-02-26 14:17 ` Vivek Goyal
2010-02-26 7:23 ` [PATCH 05/15] readahead: limit readahead size for small memory systems Christian Ehrhardt
2010-02-26 7:38 ` Wu Fengguang
2010-02-24 3:10 ` [PATCH 06/15] readahead: replace ra->mmap_miss with ra->ra_flags Wu Fengguang
2010-02-25 15:52 ` Rik van Riel [this message]
2010-02-24 3:10 ` [PATCH 07/15] readahead: thrashing safe context readahead Wu Fengguang
2010-02-25 16:24 ` Rik van Riel
2010-02-24 3:10 ` [PATCH 08/15] readahead: record readahead patterns Wu Fengguang
2010-02-25 22:37 ` Rik van Riel
2010-02-24 3:10 ` [PATCH 09/15] readahead: add tracing event Wu Fengguang
2010-02-25 22:38 ` Rik van Riel
2010-02-24 3:10 ` [PATCH 10/15] readahead: add /debug/readahead/stats Wu Fengguang
2010-02-25 22:40 ` Rik van Riel
2010-02-24 3:10 ` [PATCH 11/15] readahead: dont do start-of-file readahead after lseek() Wu Fengguang
2010-02-25 22:42 ` Rik van Riel
2010-02-24 3:10 ` [PATCH 12/15] radixtree: introduce radix_tree_lookup_leaf_node() Wu Fengguang
2010-02-25 23:13 ` Rik van Riel
2010-02-24 3:10 ` [PATCH 13/15] radixtree: speed up the search for hole Wu Fengguang
2010-02-25 23:37 ` Rik van Riel
2010-02-24 3:10 ` [PATCH 14/15] readahead: reduce MMAP_LOTSAMISS for mmap read-around Wu Fengguang
2010-02-25 23:42 ` Rik van Riel
2010-02-24 3:10 ` [PATCH 15/15] readahead: pagecache context based " Wu Fengguang
2010-02-26 1:33 ` Rik van Riel
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