Re: FreeBSD 5.3b7and poor ata performance

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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