Re: [PATCH] swapin readahead and fixes

Rik van Riel (H.H.vanRiel@phys.uu.nl)
Fri, 4 Dec 1998 15:02:56 +0100 (CET)

On Fri, 4 Dec 1998, Stephen C. Tweedie wrote:
> On Thu, 3 Dec 1998 18:56:34 +0100 (CET), Rik van Riel
> <H.H.vanRiel@phys.uu.nl> said:
>
> > The swapin enhancement consists of a simple swapin readahead.
>
> One odd thing about the readahead: you don't start the readahead until
> _after_ you have synchronously read in the first swap page of the
> cluster. Surely it is better to do the readahead first, so that you
> are submitting one IO to disk, not two?

This would severely suck when something else would be doing
a run_taskqueue(&tq_disk). It would mean that we'd read
n+1..n+15 before n itself.

OTOH, if the disk is lightly loaded it would be an advantage.
I will try it shortly (but don't know how to measure the
results :)...

cheers,

Rik -- the flu hits, the flu hits, the flu hits -- MORE
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