Date: Thu, 9 Feb 2006 17:28:30 +0100 (CET) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-scsi@FreeBSD.ORG Subject: Re: problem with low efficiency of HP Smart Array 6i under FBSD Message-ID: <200602091628.k19GSUA0020141@lurza.secnetix.de> In-Reply-To: <f0f70e5e0602090537h497b42ach@mail.gmail.com>
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peceka <peceka@gmail.com> wrote: > Our test: > #!/bin/sh > > START="0" > END="10000" > > while [ $START -lt $END ]; do > dd if=/dev/zero of=$i.iso count=100000 > /dev/null 2>&1 Where does $i come from? Doesn't seem to be initialized. Also, if you want to perform a sequential write test, it is better to use a larger block size than the default 512. For example: bs=51200 count=1000 > rm -f $i.iso > START=`expr $START+1` Better avoid fork/exec of expr(1), because you probably don't want to benchmark that. ;-) You can use the shell's arithmetic expansion: START=$(( $START + 1 )) (OK, I admit that the overhead of forking expr(1) is _much_ smaller than the dd(1) call.) > Time of executing this scripts: > FreeBSD: 149m 28s > Linux: 97m 13s Well, so Linux is about 33% faster. That's not an order of magnitude. It could be explained by differences in the file system parameters. By the way, what kind of file system did you use on FreeBSD and Linux? What parameters did you use with newfs? In fact, the difference could also be caused by the harddisks not being the same. And even if they are the same models, the location of your test files on the harddisk can be different. Most harddisks are much faster when files are stored on the lower cylinders. I don't think the difference is caused by the SCSI code. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd Any opinions expressed in this message may be personal to the author and may not necessarily reflect the opinions of secnetix in any way. "C++ is to C as Lung Cancer is to Lung." -- Thomas Funke
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