Date: Sat, 6 Jun 1998 14:18:20 -0500 (EST) From: "John S. Dyson" <dyson@FreeBSD.ORG> To: julian@whistle.com (Julian Elischer) Cc: dyson@FreeBSD.ORG, current@FreeBSD.ORG Subject: Re: New SMP perf/quality snapshot (Update) Message-ID: <199806061918.OAA06021@dyson.iquest.net> In-Reply-To: <Pine.BSF.3.95.980606101302.22014C-100000@current1.whistle.com> from Julian Elischer at "Jun 6, 98 10:17:03 am"
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Julian Elischer said: > > John, one of the changes you asked kirk and I to implement was > the change do a simple tailq (stailq) to a doubly linked list. > > Kirk asked the reason that you thought this was a speed improvement > but I think it was at a time that you were being pressured > elsewhere and couldn't answer. > > If you could supply this answer then kirk might implememt the > change in his sources and we can keep in step again.. > > I notice that your patches include this change so I'm anxious > to get everything sync'd up again.. > The reason is the way that we maintain the dirty list in vfs_subr. We need to place the metadata at the end of the dirty list. This might not be very useful for softupdates, but is very valuable for -async. We were incorrectly flushing metadata first (and unnecessarily) for -async. There is a very measurable performance improvement with this change. -- John | Never try to teach a pig to sing, dyson@freebsd.org | it just makes you look stupid, jdyson@nc.com | and it irritates the pig. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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