Re: [PATCH 10/11] readahead: dont do start-of-file readahead after lseek()

[Olivier Galibert]

On Tue, Feb 02, 2010 at 11:28:45PM +0800, 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.

Wouldn't that trigger on lseeks to end of file to get the size?

  OG.

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