Re: madvise(2) MADV_SEQUENTIAL behavior

From: Peter Zijlstra
Date: Wed Jul 16 2008 - 08:14:38 EST


On Tue, 2008-07-15 at 23:03 +0000, Eric Rannaud wrote:
> mm/madvise.c and madvise(2) say:
>
> * MADV_SEQUENTIAL - pages in the given range will probably be accessed
> * once, so they can be aggressively read ahead, and
> * can be freed soon after they are accessed.
>
>
> But as the sample program at the end of this post shows, and as I
> understand the code in mm/filemap.c, MADV_SEQUENTIAL will only increase
> the amount of read ahead for the specified page range, but will not
> influence the rate at which the pages just read will be freed from
> memory.

Correct, various attempts have been made to actually implement this, but
non made it through.

My last attempt was:
http://lkml.org/lkml/2007/7/21/219

Rik recently tried something else based on his split-lru series:
http://lkml.org/lkml/2008/7/15/465



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