Re: [resent PATCH] Re: very slow parallel read performance

Rik van Riel
2001-08-24T19:08:44Z

On Fri, 24 Aug 2001, Roger Larsson wrote:

> Not having the patch gives you another effect - disk arm is
> moving from track to track in a furiously tempo...

Fully agreed, but remember that when you reach the point
where the readahead windows are pushing each other out
you'll be off even worse.

I guess in the long run we should have automatic collapse
of the readahead window when we find that readahead window
thrashing is going on, in the short term I think it is
enough to have the maximum readahead size tunable in /proc,
like what is happening in the -ac kernels.

regards,

Rik
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