Date: Thu, 1 Oct 2009 09:10:43 -0400 From: Bill Moran <wmoran@collaborativefusion.com> To: Dieter <freebsd@sopwith.solgatos.com> Cc: freebsd-performance@freebsd.org Subject: Re: A specific example of a disk i/o problem Message-ID: <20091001091043.477f4b9b.wmoran@collaborativefusion.com> In-Reply-To: <200909301955.TAA20656@sopwith.solgatos.com> References: <3bbf2fe10909292330t753bcad1r69ae67d7e898ee35@mail.gmail.com> <200909301955.TAA20656@sopwith.solgatos.com>
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In response to Dieter <freebsd@sopwith.solgatos.com>: > > >> > My question is why is FreeBSD's disk i/o performance so bad? > > > > Here is a specific demo of one disk i/o problem I'm seeing. Should be > > > easy to reproduce? > > > > > > http://lists.freebsd.org/pipermail/freebsd-performance/2008-July/003533.html FYI, I thought I'd play around with this some in an attempt to add some useful information to the investigation. I can not reproduce the problem at all. I created a 9G file, did the cat as described in the above URL, and the man request completed in roughly the same time it did without the cat running. Just to mix it up a bit, I tried running ls -R on a large directory tree while the cat was running as well, and performance did not seem to be significantly impacted there, either. I ran the tests on my work machine, which is a Dell Optiplex 960 running FreeBSD 7.2-RELEASE-p3 i386. Some relevant dmesg stuff: atapci0: <Intel ATA controller> port 0xfe80-0xfe87,0xfe90-0xfe93,0xfea0-0xfea7,0xfeb0-0xfeb3,0xfef0-0xfeff irq 18 at device 3.2 on pci0 atapci1: <Intel ICH8 SATA300 controller> port 0xfe00-0xfe07,0xfe10-0xfe13,0xfe20-0xfe27,0xfe30-0xfe33,0xfec0-0xfedf mem 0xff970000-0xff9707ff irq 18 at device 31.2 on pci0 ad14: 476940MB <Seagate ST3500630AS 3.AAK> at ata7-master SATA150 -- Bill Moran Collaborative Fusion Inc. http://people.collaborativefusion.com/~wmoran/
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