Date: Sat, 23 Sep 2000 00:06:05 +0200 From: Bernd Walter <ticso@cicely5.cicely.de> To: Mike Smith <msmith@freebsd.org> Cc: Marius Bendiksen <mbendiks@eunet.no>, freeBSD-scsi@freebsd.org Subject: Re: disable write caching with softupdates? Message-ID: <20000923000605.A448@cicely5.cicely.de> In-Reply-To: <200009211710.KAA00784@mass.osd.bsdi.com>; from msmith@freebsd.org on Thu, Sep 21, 2000 at 10:10:06AM -0700 References: <Pine.BSF.4.05.10009211537460.38959-100000@login-1.eunet.no> <200009211710.KAA00784@mass.osd.bsdi.com>
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On Thu, Sep 21, 2000 at 10:10:06AM -0700, Mike Smith wrote: > > > > OK, I played a bit with that, the only info I can see I get from the > > > > higher levels is the BIO_ORDERED bit, so I tried to flush the cache > > > > each time I get one of those, _bad_ idea, 10% performance loss... > > > > > That's the price of having a recoverable file system. See Seltzer, Ganger, > > > > Not necessarily. > > Er, you're being both contrary and plain wrong. It's a fundamental > assumption of the softupdates implementation that it is possible to issue > an ordered write and have it complete in an ordered fashion. Now I'm very confused ;( That's what Matthew Dillon wrote on -current in May: : Wait a sec... softupdates does not depend on write ordering. Softupdates : issues all non-conflicting writes in parallel and doesn't care what order : they are written to the disk. When those complete, softupdates will then : followup with all the writes that depend on the original set. As far as I know Kirk McKusick had bad expiriences with disks not honouring the ordered stuff. What is the truth? -- B.Walter COSMO-Project http://www.cosmo-project.de ticso@cicely.de Usergroup info@cosmo-project.de To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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