Date: Mon, 2 May 2005 22:56:57 +0100 From: "Steven Hartland" <killing@multiplay.co.uk> To: "Poul-Henning Kamp" <phk@phk.freebsd.dk> Cc: Eric Anderson <anderson@centtech.com> Subject: Re: Very low disk performance on 5.x Message-ID: <00fe01c54f61$df220d60$b3db87d4@multiplay.co.uk> References: <19879.1115061648@critter.freebsd.dk>
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----- Original Message -----
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
> On -current and 5.4 you don't have to make partitions if you
> intend to use the entire disk (and provided you don't want
> to boot from it). You can simply:
>
> newfs /dev/da0
> mount /dev/da0 /where_ever
/dev/da0: 1526216.3MB (3125691008 sectors) block size 16384, fragment size 2048
using 8306 cylinder groups of 183.77MB, 11761 blks, 23552 inodes.
mount /dev/da0 /mnt
dd if=/dev/zero of=/mnt/testfile bs=64k count=100000
100000+0 records in
100000+0 records out
6553600000 bytes transferred in 44.424588 secs (147521908 bytes/sec)
/usr/bin/time -h dd of=/dev/null if=/mnt/testfile bs=64k count=100000
100000+0 records in
100000+0 records out
6553600000 bytes transferred in 48.150473 secs (136106658 bytes/sec)
48.27s real 0.01s user 12.33s sys
/usr/bin/time -h cat /mnt/testfile > /dev/null
48.12s real 0.26s user 14.92s sys
Raw read:
/usr/bin/time -h dd of=/dev/null if=/dev/da0 bs=64k count=100000
100000+0 records in
100000+0 records out
6553600000 bytes transferred in 32.028544 secs (204617482 bytes/sec)
32.02s real 0.02s user 2.73s sys
/usr/bin/time -h dd of=/dev/null if=/dev/da0 bs=1m count=6000
6000+0 records in
6000+0 records out
6291456000 bytes transferred in 31.518195 secs (199613460 bytes/sec)
31.51s real 0.00s user 1.87s sys
> One thing you could try is to use a larger block/fragment size
> on your filesystem. Try:
>
> newfs -b 32768 -f 4096 /dev/da0
/dev/da0: 1526216.3MB (3125691008 sectors) block size 32768, fragment size 4096
using 2063 cylinder groups of 740.00MB, 23680 blks, 47360 inodes.
/usr/bin/time -h dd if=/dev/zero of=/mnt/testfile bs=64k count=100000
100000+0 records in
100000+0 records out
6553600000 bytes transferred in 35.237328 secs (185984590 bytes/sec)
35.34s real 0.07s user 28.81s sys
/usr/bin/time -h dd of=/dev/null if=/mnt/testfile bs=64k count=100000
100000+0 records in
100000+0 records out
6553600000 bytes transferred in 39.154845 secs (167376477 bytes/sec)
39.16s real 0.01s user 14.33s sys
Slower than the default :(
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