From owner-freebsd-scsi Mon Mar 12 14:20: 2 2001 Delivered-To: freebsd-scsi@freebsd.org Received: from mailman.zeta.org.au (mailman.zeta.org.au [203.26.10.16]) by hub.freebsd.org (Postfix) with ESMTP id 5F80937B718; Mon, 12 Mar 2001 14:19:57 -0800 (PST) (envelope-from bde@zeta.org.au) Received: from bde.zeta.org.au (bde.zeta.org.au [203.2.228.102]) by mailman.zeta.org.au (8.9.3/8.8.7) with ESMTP id JAA18673; Tue, 13 Mar 2001 09:18:01 +1100 Date: Tue, 13 Mar 2001 09:17:47 +1100 (EST) From: Bruce Evans X-Sender: bde@besplex.bde.org To: Alfred Perlstein Cc: Soren Schmidt , Kevin Oberman , scsi@FreeBSD.ORG, gibbs@FreeBSD.ORG Subject: Re: Disk I/O problem in 4.3-BETA In-Reply-To: <20010312132922.Y18351@fw.wintelcom.net> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Mon, 12 Mar 2001, Alfred Perlstein wrote: > > > Mr ATA, is there no ATA command to "syncronize cache" like in SCSI? > > > > Yes, there is, and the ATA driver even uses it, the problem is WHEN > > to use it. I originally made it flush the cache if a write contained > > the BIO_ORDERED bit, but that doesn't work with softupdates.. > > If somebody can come up with a way to tell me when I need to flush > > the write cache, then I'll happily add that.. > > Justin, I've heard that SCSI knows when to send sync-cache commands > to the disks, how does the driver know when to do this based on > the bio request? > > It'd be nice to get this fixed for 4.3 because I've noticed terrible > perf for laptops because of the complete lack of write caching... :( I just put "options ATA_ENABLE_WC" in all my config files. Changing the default for write caching from enabled to disabled in rev.1.92 of ata_disk.c was a huge pessimisation, but it is probably currently required for soft updates. I don't use soft updates ... Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message