Date: Sat, 19 Feb 2011 11:37:20 +0300 (MSK) From: Dmitry Morozovsky <marck@rinet.ru> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-scsi@freebsd.org, stable@freebsd.org, "Kenneth D. Merry" <ken@freebsd.org> Subject: Re: mps(4) driver (LSI 6Gb SAS) commited to stable/8 Message-ID: <alpine.BSF.2.00.1102191136190.14809@woozle.rinet.ru> In-Reply-To: <20110218231306.GA69028@icarus.home.lan> References: <20110218164209.GA77903@nargothrond.kdm.org> <alpine.BSF.2.00.1102190104280.14809@woozle.rinet.ru> <20110218225204.GA84087@nargothrond.kdm.org> <alpine.BSF.2.00.1102190203470.14809@woozle.rinet.ru> <20110218231306.GA69028@icarus.home.lan>
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On Fri, 18 Feb 2011, Jeremy Chadwick wrote: JC> > KDM> The best stress test I have found has been to just do a single sequential JC> > KDM> write stream with ZFS. i.e.: JC> > KDM> JC> > KDM> cd /path/to/zfs/pool JC> > KDM> dd if=/dev/zero of=foo bs=1M JC> > KDM> JC> > KDM> Just let it run for a long period of time and see what happens. JC> > JC> > Well, provided that I'm plannign to use ZFSv28 to be in place, wouldn't be JC> > /dev/random more appropriate? JC> JC> No -- /dev/urandom maybe, but not /dev/random. /dev/urandom will also JC> induce significantly higher CPU load than /dev/zero will. Don't forget JC> that ZFS is a processor-centric (read: no offloading) system. We're not on Linux: root@beaver:/FreeBSD/src.8# l /dev/*random crw-rw-rw- 1 root wheel 0, 23 Feb 15 13:50 /dev/random lrwxr-xr-x 1 root wheel 6 Feb 15 13:50 /dev/urandom@ -> random JC> I tend to try different block sizes (starting at bs=8k and working up to JC> bs=256k) for sequential benchmarks. The "sweet spot" on most disks I've JC> found is 64k. Otherwise use benchmarks/bonnie++. Ah yes, bonnie++ was on my list too, thanks for the reminder. -- Sincerely, D.Marck [DM5020, MCK-RIPE, DM3-RIPN] [ FreeBSD committer: marck@FreeBSD.org ] ------------------------------------------------------------------------ *** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru *** ------------------------------------------------------------------------
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