Subject: Re: 1.4.1, APM, SCSI disk spin down how?
To: Chris Tribo <>
From: Manuel Bouyer <>
List: current-users
Date: 07/27/2000 22:20:44
On Wed, Jul 26, 2000 at 05:08:45PM -0400, Chris Tribo wrote:
> [...]
> 	On the flip side, what does the general population think about
> creating a PI DPM (Disk Power Management?) daemon that works for non-APM
> and/or non-i386 machines?

I've been thinking about this for some time now ... but I'm not sure it can be
reasonably done in userland. e.g. the kernel knows if it has dirty buffers for
this disk, and then may flush them before spining down to avoid spining up
again just to flush them later when needed.
Similary, the buffer management code may prefer already-spin up disks
when there is buffer shortage and it needs to free some. Similary goes
for swap ...

Manuel Bouyer, LIP6, Universite Paris VI.