Date: Wed, 16 Mar 2011 21:37:10 +0100 From: Ivan Voras <ivoras@freebsd.org> To: Garrett Cooper <gcooper@freebsd.org> Cc: svn-src-head@freebsd.org, Roman Divacky <rdivacky@freebsd.org>, src-committers@freebsd.org, svn-src-all@freebsd.org Subject: Re: svn commit: r219699 - head/sys/kern Message-ID: <AANLkTinOAWW%2B6a2WmhAjoqmj4V8aZkRHPJ%2BumVq=0onb@mail.gmail.com> In-Reply-To: <AANLkTiny%2Bgzdtc078Wm_dHC9AsNG_xMGeLkz_5U8iu8g@mail.gmail.com> References: <201103161622.p2GGMxNp097642@svn.freebsd.org> <20110316174642.GB6367@freebsd.org> <AANLkTika25WRx=TWJXeNg_2786U11ff7_O68DkBz1oKc@mail.gmail.com> <AANLkTiny%2Bgzdtc078Wm_dHC9AsNG_xMGeLkz_5U8iu8g@mail.gmail.com>
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On 16 March 2011 20:59, Garrett Cooper <gcooper@freebsd.org> wrote: > On Wed, Mar 16, 2011 at 12:51 PM, Ivan Voras <ivoras@freebsd.org> wrote: >> On 16 March 2011 18:46, Roman Divacky <rdivacky@freebsd.org> wrote: >>> >>> On Wed, Mar 16, 2011 at 04:22:59PM +0000, Ivan Voras wrote: >>> > Author: ivoras >>> > Date: Wed Mar 16 16:22:59 2011 >>> > New Revision: 219699 >>> > URL: http://svn.freebsd.org/changeset/base/219699 >>> > >>> > Log: >>> > =C2=A0 The hardware has caught up; improvements are now observed even= at 128, >>> > =C2=A0 but stay conservative and bump read_max to "only" 64 (it will = probably be >>> > =C2=A0 a good idea to increase this to 128 after the next major relea= se). >>> >>> how did you measure this? >> >> Specifically for this commit: my desktop 2xSATA 7200 RPM drives, >> gmirror, single read "dd" stream, bs=3D1m. (Are there any ready read >> multi-stream read tests which are not trivial i.e. they start from >> different positions in the file?) > > Would be interesting to see how well things work with the new > geom_raid bits and with other drives (SAS, SCSI). Yes, I'd be interested in that; I'll try it when I get the chance to test new hardware. For now, there's a report (which actually inspired me to retest and commit this) from someone who tried this on 2x 15k RPM SAS drives, with much better results using read_max=3D128 (thread "gmirror performance" on freebsd-fs@). I estimate that because his drives were 15kRPM from the start, the improvement isn't as drastic going from 8 to 128 as on these SATA drives I tested on (faster seeks). He went from ~~ 195 MB/s to ~~ 258 MB/s while I go from ~~ 50 MB/s to ~~ 140 MB/s.
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