Date: Wed, 20 Oct 2004 09:20:28 -0400 From: Mike Tancsa <mike@sentex.net> To: fandino@ng.fadesa.es, freebsd-current@freebsd.org Subject: Re: FreeBSD 5.3b7and poor ata performance Message-ID: <6.1.2.0.0.20041019121353.026745f8@64.7.153.2> In-Reply-To: <41753A8F.4040809@ng.fadesa.es> References: <20041015190638.C5A0E5D04@ptavv.es.net> <41715E7F.7060509@ng.fadesa.es> <20041018100045.f8koww0skcco0woo@www.sweetdreamsracing.biz> <4173D66F.6010200@DeepCore.dk> <4173F2E9.7010407@ng.fadesa.es> <417406E3.9010706@DeepCore.dk> <4174FD04.8040000@ng.fadesa.es> <20041019104525.ikgw8kcw8sw480os@www.sweetdreamsracing.biz> <41753A8F.4040809@ng.fadesa.es>
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At 12:02 PM 19/10/2004, fandino wrote:
># dd if=/dev/ad4 of=/dev/null bs=1024k count=1024
>1024+0 records in
>1024+0 records out
>1073741824 bytes transferred in 30.606110 secs (35082597 bytes/sec)
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)
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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