Subject: Re: i/o scheduling (was Re: NEW_BUFQ_STRATEGY)
To: Daniel Carosone <>
From: Manuel Bouyer <>
List: tech-kern
Date: 12/16/2003 22:38:42
On Mon, Dec 15, 2003 at 04:37:07PM +1100, Daniel Carosone wrote:
> On Sun, Dec 14, 2003 at 12:41:58PM +0900, YAMAMOTO Takashi wrote:
> > three queues are for
> > [...]
> > 	- time non sensitive requests.
> > 		e.g. delayed writes
> Something that's been discussed before, but is worth mentioning again
> at this point - I'd just love to see a mechanism that allowed
> really-not-very-interesting requests (the canonical example being
> atime updates) to wait ~forever if the disk is not spun up, and then
> to proceed when some other higher-priority request wakes up the disk
> (or there are too many such waiting?)
> That needs some help from the layers above, and probably below.

I'd like to see this too. IMHO, this can share the same queue as delayed
writes. Only wake up the disk when there's too much requests in the queue, or
we have something else to do.
This would also prevent writes to log files to wake up the disk.

Manuel Bouyer <>
     NetBSD: 24 ans d'experience feront toujours la difference