Date: Tue, 19 Oct 2004 14:12:58 -0700 From: Julian Elischer <julian@elischer.org> To: Mike Jakubik <mikej@rogers.com> Cc: freebsd-current@freebsd.org Subject: Re: FreeBSD 5.3b7and poor ata performance Message-ID: <4175835A.2050609@elischer.org> In-Reply-To: <4296.192.168.0.188.1098219697.squirrel@192.168.0.188> 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> <4296.192.168.0.188.1098219697.squirrel@192.168.0.188>
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Mike Jakubik wrote: >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. > How do you disable GEOM? I believe it is no longer optional. Everythi g runs through geom. you may however be not installing some modules.. > > >
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