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.Received on Tue Oct 19 2004 - 19:01:45 UTC
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