Date: Tue, 19 Oct 2004 17:01:37 -0400 (EDT) From: "Mike Jakubik" <mikej@rogers.com> To: "Julian Elischer" <julian@elischer.org> Cc: freebsd-current@freebsd.org Subject: Re: FreeBSD 5.3b7and poor ata performance Message-ID: <4296.192.168.0.188.1098219697.squirrel@192.168.0.188> In-Reply-To: <41757B81.5060700@elischer.org> 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> <4129.192.168.0.188.1098211592.squirrel@192.168.0.188> <41757B81.5060700@elischer.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Julian Elischer said: > > Mike Jakubik wrote: >>Out of curiosity, i ran this on one of our production servers, which runs >>on a dual Xeon MB, with SCSI raid-10 setup, and to my surprise here are >>the results: >> >>CPU: Intel(R) Xeon(TM) CPU 2.80GHz (2799.22-MHz 686-class CPU) >>real memory = 2146959360 (2047 MB) >>avail memory = 2099650560 (2002 MB) >>FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs >> >>da0 at asr0 bus 0 target 0 lun 0 >>da0: <ADAPTEC RAID-10 3B0A> Fixed Direct Access SCSI-2 device >> >>FreeBSD 5.3-BETA4 #0: Sun Sep 12 13:09:43 EDT 2004 >> >>(Custom kernel, no debugging) >> >># dd if=/dev/da0 of=/dev/null bs=1m count=200 >>200+0 records in >>200+0 records out >>209715200 bytes transferred in 6.225309 secs (33687517 bytes/sec) >> >>Why is a SCSI raid-10 system slower than a plain IDE disk? Something is >>wrong here. >> > > I BELIEVE (without empirical proof) that the new scheme of running IO > through the geom threads > requires a higher degree of smartness from the scheduler than before, > where IO was done either by interrupt > or by the calling (already running) thread. > > Make sure you have preemption enabled, and make sure that HTT is turned > off. (HTT is a DOG that slows down > almost everything except processes that have a lot of FP work). I do not use GEOM, all GEOM related stuff is is disabled from the kernel. HTT is disabled in the bios already. Im using SCHED_4BSD, no prememtion however. I will update this box to a more recent releng_5 soon, and try again. Still, this seems pretty bad for server class hardware.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4296.192.168.0.188.1098219697.squirrel>