Messages in this thread | | | Subject | Re: [PATCH] fix readahead breakage for sequential after random reads | From | Ram Pai <> | Date | 26 Jul 2004 16:56:58 -0700 |
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Andrew, Yes the patch fixes a valid bug.
RP
On Mon, 2004-07-26 at 16:29, Andrew Morton wrote: > Miklos Szeredi <miklos@szeredi.hu> wrote: > > > > Current readahead logic is broken when a random read pattern is > > followed by a long sequential read. The cause is that on a window > > miss ra->next_size is set to ra->average, but ra->average is only > > updated at the end of a sequence, so window size will remain 1 until > > the end of the sequential read. > > > > This patch fixes this by taking the current sequence length into > > account (code taken from towards end of page_cache_readahead()), and > > also setting ra->average to a decent value in handle_ra_miss() when > > sequential access is detected. > > Thanks. Do you have any performance testing results from this patch? >
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