FreeBSD 5.3b7and poor ata performance
fandino
fandino at ng.fadesa.es
Thu Oct 21 00:35:22 PDT 2004
Mike Tancsa wrote:
> Its strange that you do not see any difference in speed when reading
> from the device directly vs a file ? I see quite a difference in my
> setup on a RELENG_5 box and not so much a difference on a RELENG_4 box.
> Perhaps as someone suggested, the GEOM layer ?
>
> e.g. create a file with junk larger than your RAM. (the machine below
> has 256M)
-- same mobo and same disks --
OpenBSD 3.5:
dd if=/mnt/aa of=/dev/null bs=1024k count=1024
1024+0 records in
1024+0 records out
1073741824 bytes transferred in 18.743 secs (57287584 bytes/sec)
FreeBSD 5.3rc1:
# dd if=/mnt/aa of=/dev/null bs=1024k count=1024
1024+0 records in
1024+0 records out
1073741824 bytes transferred in 42.215597 secs (25434719 bytes/sec)
> On FreeBSD 915.sentex.ca 5.3-STABLE FreeBSD 5.3-STABLE #1: Mon Oct 18
>
> 915# dd if=/dev/urandom of=/usr/tmp/b bs=1024k count=1024
> 1024+0 records in
> 1024+0 records out
> 1073741824 bytes transferred in 40.103750 secs (26774100 bytes/sec)
>
> Now, for the read speed
>
> 915# dd if=/dev/ad2s1d of=/dev/null bs=1024k count=1000
> 256+0 records in
> 256+0 records out
> 268435456 bytes transferred in 4.606747 secs (58270065 bytes/sec)
> 915# dd if=/dev/ad2 of=/dev/null bs=1024k count=1000
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes transferred in 18.049106 secs (58095730 bytes/sec)
> 915# dd if=/usr/tmp/b of=/dev/null bs=1024k count=1000
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes transferred in 29.876008 secs (35097594 bytes/sec)
> 915# dd if=/usr/tmp/b of=/dev/null bs=1024k count=1000
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes transferred in 29.952459 secs (35008011 bytes/sec)
> 915#
>
> 58 vs 35.
>
> Yet on a RELENG_4 machine, the difference is not nearly as acute.
> Considering the RELENG_4 box is a Celeron 1000 blasting a ad0: 38166MB
> <ST340014A> [77545/16/63] at ata0-master UDMA100 I am surprised by the
> results.
>
> proxy-a# dd if=/dev/ad0s1e of=/dev/null bs=1024k count=1000
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes transferred in 20.884694 secs (50207870 bytes/sec)
> proxy-a#
> proxy-a# dd if=/usr/tmp/b of=/dev/null bs=1024k count=1000
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes transferred in 24.908032 secs (42097907 bytes/sec)
>
>
> ---Mike
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