Re: /proc/sys/vm/(max|min)-readahead effect????

Roy Sigurd Karlsbakk (roy@karlsbakk.net)
Thu, 6 Dec 2001 12:31:03 +0100 (CET)

Thanks!

It works

On Wed, 5 Dec 2001, Andrew Morton wrote:

> 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).
>
> -
>

--
Roy Sigurd Karlsbakk, MCSE, MCNE, CLS, LCA


Computers are like air conditioners.
They stop working when you open Windows.


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