Re: [PATCH] Improve heuristic detecting sequential reads

From: Andi Kleen
Date: Tue Apr 10 2007 - 17:58:48 EST


Jan Kara <jack@xxxxxxx> writes:

> Hello!
>
> In thread http://lkml.org/lkml/2007/3/9/403, we discussed a problem
> with the current heuristic for detecting sequential IO in
> do_generic_mapping_read() - for small files a page is marked as accessed
> only once which can cause a performance problems.
> Attached is a patch that improves the heuristic by introducing a
> ra.offset variable so now we can reliably detect sequetial reads.
> The patch replaces Nick's patch from http://lkml.org/lkml/2007/3/15/177
> (Nick has acked to replace the patch). Could you please put the patch
> into -mm?

There's a much more complete patchkit for this that gets reposted
regularly on l-k. Perhaps it would make sense to test that first?

-Andi
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