Subject: Re: write cache on ATA drives
To: Thor Lancelot Simon <tls@rek.tjls.com>
From: Manuel Bouyer <bouyer@antioche.eu.org>
List: tech-kern
Date: 12/09/2002 22:20:21
On Thu, Dec 05, 2002 at 06:25:33PM -0500, Thor Lancelot Simon wrote:
> What Windows does, evidently, is to disable and then re-enable write-back
> caching as barriers around performing a synchronous I/O to the drive.  This
> forces a cache flush, so you know the sync I/O went out, while letting the
> drive continue to reorder async I/O to normal files, retaining much of the
> performance benefit.  With softdep, you'd retain most of the rest -- as
> much as you could _safely_ retain, anyway.

This is easy to do. Unfortunably, I don't think the filesystems will pass
us this info ...

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 23 ans d'experience feront toujours la difference
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