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SubjectRe: /proc/sys/vm/(max|min)-readahead effect????
Roy Sigurd Karlsbakk wrote:
>
> hi all
>
> I've just upgraded to 2.4.16 to get /proc/sys/vm/(max|min)-readahead
> available. I've got this idea...
>
> If lots of files (some hundered) are read simultaously, I waste all the
> i/o time in seeks. However, if I increase the readahead, it'll read more
> data at a time, and end up with seeking a lot less.
>
> The harddrive I'm testing this with, is a cheap 20G IDE drive.

/proc/sys/vm/*-readhead is a no-op for IDE. It doesn't do
anything. You must use
echo file_readahead:100 > /proc/ide/ide0/hda/settings
to set the readhead to 100 pages (409600 bytes).

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