Date: Wed, 20 Dec 2006 23:38:07 +1300 From: Mark Kirkwood <markir@paradise.net.nz> To: JoaoBR <joao@matik.com.br> Cc: freebsd-stable@freebsd.org Subject: Re: Cached file read performance with 6.2-PRERELEASE Message-ID: <4589128F.9030404@paradise.net.nz> In-Reply-To: <200612200816.51043.joao@matik.com.br> References: <45888C68.10305@paradise.net.nz> <200612200618.12826.joao@matik.com.br> <4589045C.1050206@paradise.net.nz> <200612200816.51043.joao@matik.com.br>
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JoaoBR wrote: > On Wednesday 20 December 2006 07:37, Mark Kirkwood wrote: >> JoaoBR wrote: >>> On Tuesday 19 December 2006 22:05, Mark Kirkwood wrote: >>>> $ dd of=/dev/null if=/tmp/file bs=32k # read it >>>> 819200000 bytes transferred in 1.801944 secs (454620117 bytes/sec) >>> hum, look my releng_6: >>> >>> # dd of=/dev/null if=/c/c1/file bs=32k >>> 819200000 bytes transferred in 0.896507 secs (913768635 bytes/sec) >> Hmm - so your machine reads memory twice as fast as mine, which is >> great! but I'm not sure it actually shows anything useful ... let me >> guess - a P4 with DDR or DDR2 memory??? maybe if we look a bit harder at >> buffer cache performance you could get 1.2GB/s or more - wouldn't that >> be a good thing? > > > oh! if it is useful or not seems to be your call, you was the one who said > linux is twice as fast as freebsd :) Oh dear :-), I'm actually a FreeBSD guy, I just happen to need a Linux box because the product I'm working on does not build on FreeBSD (yet....heh heh). > > it's a dual-opteron with ddr400 I just compiled world with no tweaks and > standard newfs options > > if you're interested I send new results after completing my setup > Sorry JoaoBR - I am interested! I was however trying to point out that as your machine is different from mine (opteron and ddr*400* as opposed to PIII and pc133), the fact that it is faster is not telling us anything about whether releng_6 performance on cached file reads could be improved! In fact if you note that the PIII HW *can* actually do 700MB/s, it suggests that your HW is capable of considerably more than 900MB/s - given that opteron's have excellent cpu to memory bandwidth, and the speed of your memory! Cheers Mark
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