Date: Tue, 19 Oct 2004 23:45:18 -0400 (EDT) From: "Mike Jakubik" <mikej@rogers.com> To: "Scott Long" <scottl@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: FreeBSD 5.3b7and poor ata performance Message-ID: <1230.192.168.0.188.1098243918.squirrel@192.168.0.188> In-Reply-To: <4175D269.208@freebsd.org> References: <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> <4129.192.168.0.188.1098211592.squirrel@192.168.0.188> <20041019200908.GA655@frontfree.net> <4259.192.168.0.188.1098217092.squirrel@192.168.0.188> <20041020024908.GA3797@frontfree.net> <4175D269.208@freebsd.org>
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Scott Long said: > Xin LI wrote: >> Hi, Mike >> >> On Tue, Oct 19, 2004 at 04:18:12PM -0400, Mike Jakubik wrote: >> >>>Xin LI said: >>> >>> >>>>Unfortunatelly I can reproduce similiar problem when using Ultra320 >>>> under >>>>mpt(4) and a version of Adaptec's SCSI card (maybe aic, or something >>>> else, >>>>which I have to go to my office to find out). Additionally the problem >>>> is >>>>not FreeBSD specific, with a Linux installation, it shows poor >>>> performance >>>>too. (No RAID configuration, though). >>>> >>>>I found that block size does influence performance greatly. With a >>>> block >>>>size of 131072 I got peak read performance at about 70MB/s, but that's >>>>all. >>>>I did not have the necessary knowledge at the time I have did the test >>>>last >>>>month, so I got only the result and thought that I have made something >>>>wrong and hoped someone to correct me with no luck :-( >>> >>>Hrm, i tried your block size, and the performance is even worse: >>> >>># dd if=/dev/da0 of=/dev/null bs=131072 count=2000 >>>2000+0 records in >>>2000+0 records out >>>262144000 bytes transferred in 8.688651 secs (30170852 bytes/sec) >> >> >> You may want to try other block sizes, like 65536, 262144, 524288, >> 1048576 >> or so. The peak performance block size depends heavily on hardware... >> >> Cheers, > > This won't really matter. physio will chop the blocks up into 128k > segments, and GEOM will cut them again into 64k segments. Other than > a minor amount of coelscing in these stages, it won't make a difference. Considering phk's comments, i still find it odd that a scsi based (brand new seagate cheetahs) raid 10 array would perform so poorly in transfer rates compared to a single ata drive. I ran diskinfo -t on the array, and it just confirmed that the transfer rates are lacking, the seek rate is however 3x as fast as the ata drives.
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