Re: [PATCH 11/15] readahead: dont do start-of-file readahead afterlseek()

From: Rik van Riel
Date: Thu Feb 25 2010 - 17:43:55 EST


On 02/23/2010 10:10 PM, Wu Fengguang wrote:
Some applications (eg. blkid, id3tool etc.) seek around the file
to get information. For example, blkid does
seek to 0
read 1024
seek to 1536
read 16384

The start-of-file readahead heuristic is wrong for them, whose
access pattern can be identified by lseek() calls.

So test-and-set a READAHEAD_LSEEK flag on lseek() and don't
do start-of-file readahead on seeing it. Proposed by Linus.

Acked-by: Linus Torvalds<torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Wu Fengguang<fengguang.wu@xxxxxxxxx>

Acked-by: Rik van Riel <riel@xxxxxxxxxx>
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