Date: Sat, 1 Apr 2000 17:03:24 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Richard Wendland <richard@netcraft.com> Cc: Paul Richards <paul@originative.co.uk>, Alfred Perlstein <bright@wintelcom.net>, Poul-Henning Kamp <phk@critter.freebsd.dk>, current@FreeBSD.ORG, fs@FreeBSD.ORG Subject: Re: FreeBSD random I/O performance issues Message-ID: <200004020103.RAA43602@apollo.backplane.com> References: <200003221544.PAA08760@ns0.netcraft.com>
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I've committed an 80% fix for the random seek / write
performance issue. The rest of the fix will come later
when Kirk commits his shared-lock-buffer-cache idea.
I've committed it into -current and will MFC it into
-stable in a week if there aren't any problems. I
do not intend to MFC it into 3.x.
This should solve most of the random-I/O latency issues
with read-after-write on buffers. Basically what
had to be done was to continue to call the clustering
code as before (so reallocblks still gets called), but
only issue write_behind I/O if the writes are
generally sequential. If the writes are random, even
big writes, we do not issue write-behind I/O.
-Matt
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