Re: Unresponiveness of 2.4.16

From: Mike Fedyk (mfedyk@matchmail.com)
Date: Tue Nov 27 2001 - 21:34:29 EST


On Tue, Nov 27, 2001 at 06:13:41PM -0800, Andrew Morton wrote:
> Dieter N?tzel wrote:
> > Don't forget to tune max-readahead.
>
> Yes. Readahead is fairly critical and there may be additional fixes
> needed in this area.
>
> Someone recently added the /proc/sys/vm/max_readahead (?) tunable.
> Beware of this. It only works for device drivers which do not
> populate their own readhead table. For IDE, it *looks* like
> it works, but it doesn't. For IDE, the only way to alter VM
> readahead is via
>
> echo file_readahead:N > /proc/ide/ide0/hda/settings
>
> where N is in kilobytes in 2.4.16 kernels.

Any idea which drivers it will/won't work on? ie, "almost all ide" or
"almost none of the ide driers"?

>In earlier kernels
> it's kilopages (!).

Isn't this part of the max-readahead patch?

Does /proc/sys/vm/max_readahead affect scsi in any way?

What layer does /proc/sys/vm/max_readahead affect? Block? FS?

MF
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