Date: Tue, 03 May 2005 08:45:49 +0200 From: Martin Nilsson <martin@gneto.com> To: Petri Helenius <pete@he.iki.fi> Cc: Eric Anderson <anderson@centtech.com> Subject: Re: Very low disk performance on 5.x Message-ID: <42771E1D.9070408@gneto.com> In-Reply-To: <42770026.80901@he.iki.fi> References: <19879.1115061648@critter.freebsd.dk> <20050502214208.M87351@fledge.watson.org> <42770026.80901@he.iki.fi>
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Petri Helenius wrote: > I noticed that changing vfs.read_max from the default 8 to 16 has a > dramatic effect on sequential read performance. Increasing it further > did not have measurable effect. Increasing MAXPHYS in sys/param.h from 128k to 1M increased sequential read thruput on my MegaRAID 1600 from 100MB/s to 190MB/s measured on 5.4 #RAID0 7*36GB MegaRAID 1600 MAXPHYS=1M t125# dd if=/dev/amrd0 of=/dev/null bs=1024k count=1024 1073741824 bytes transferred in 5.559722 secs (193128691 bytes/sec) It had no effect on bonnie so the filesystem probaby never issues block-reads that large, I'll try the above sysctl. 190MB/s is pretty good considering that the card is in a ServerWorks LE chipped P3 and that the internal datapath on the Elite 1600 is only 64-bit/33MHz. /Martin
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