Re: Very low disk performance on 5.x

From: Steven Hartland (killing_at_multiplay.co.uk)
Date: 05/02/05

  • Next message: Arne : "Re: Very low disk performance on 5.x" 
    To: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
Date: Mon, 2 May 2005 22:56:57 +0100

    ----- 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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  • Next message: Arne : "Re: Very low disk performance on 5.x"

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