Date: Thu, 21 Sep 2000 20:43:49 +0000 (GMT)
From: Terry Lambert <tlambert@primenet.com>
To: sos@freebsd.dk (Soren Schmidt)
Cc: Stephen.Byan@quantum.com (Stephen Byan), mbendiks@eunet.no ('Marius Bendiksen'), fs@FreeBSD.ORG, sos@FreeBSD.ORG, freeBSD-scsi@FreeBSD.ORG
Subject: Re: disable write caching with softupdates?
Message-ID: <200009212043.NAA16157@usr08.primenet.com>
In-Reply-To: <200009211502.RAA92422@freebsd.dk> from "Soren Schmidt" at Sep 21, 2000 05:02:57 PM
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> ATA driver with flush cache on "BIO_ORDERED": > 3964.18 real 0.00 user 2870.09 sys > > ATA driver with write cache disabled: > 4423.30 real 0.00 user 2871.87 sys > > So, having the write cache there definitly is a win. > > I'll try this on TWO IBM DTLA drives with tags enabled and see what gives.. > > Anything else you want me to mess with now we are at it ? I suspect that much of this difference is unnecessary I/O bus transactions to recover "lost" cached data resulting from the inode/vnode disassociation. Try significantly increasing the number of vnodes in your system, and the ihash pool size, and see if it has any effect on the second set of numbers, by reducing the bus overhead through unnecessary reclaims. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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