Date: Wed, 20 Dec 2006 13:56:20 +0100 From: "O. Hartmann" <ohartman@zedat.fu-berlin.de> To: JoaoBR <joao@matik.com.br> Cc: freebsd-stable@freebsd.org, Mark Kirkwood <markir@paradise.net.nz> Subject: Re: Cached file read performance with 6.2-PRERELEASE Message-ID: <458932F4.5010107@zedat.fu-berlin.de> In-Reply-To: <200612200618.12826.joao@matik.com.br> References: <45888C68.10305@paradise.net.nz> <200612200618.12826.joao@matik.com.br>
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JoaoBR wrote: > On Tuesday 19 December 2006 22:05, Mark Kirkwood wrote: >> In the process of investigating performance in another area I happened >> to be measuring sequential cached reads (in a fairly basic manner): >> >> $ dd if=/dev/zero of=/tmp/file bs=8k count=100000 # create file >> 819200000 bytes transferred in 4.849394 secs (168928321 bytes/sec) hartmann: dd if=/dev/zero of=/tmp/file bs=8k count=100000 100000+0 records in 100000+0 records out 819200000 bytes transferred in 18.540244 secs (44184964 bytes/sec) hartmann: dd if=/dev/zero of=/tmp/file bs=8k count=100000 100000+0 records in 100000+0 records out 819200000 bytes transferred in 18.047627 secs (45391009 bytes/sec) >> >> $ dd of=/dev/null if=/tmp/file bs=8k # read it >> 819200000 bytes transferred in 2.177922 secs (376138354 bytes/sec) hartmann: dd of=/dev/null if=/tmp/file bs=8k 100000+0 records in 100000+0 records out 819200000 bytes transferred in 1.898039 secs (431603332 bytes/sec) >> $ dd of=/dev/null if=/tmp/file bs=8k # read again >> 819200000 bytes transferred in 2.178407 secs (376054620 bytes/sec) hartmann: dd of=/dev/null if=/tmp/file bs=8k 100000+0 records in 100000+0 records out 819200000 bytes transferred in 1.328635 secs (616572658 bytes/sec) >> 819200000 bytes transferred in 2.178407 secs (376054620 bytes/sec) >> $ dd of=/dev/null if=/tmp/file bs=32k # read it >> 819200000 bytes transferred in 1.801944 secs (454620117 bytes/sec) hartmann: dd of=/dev/null if=/tmp/file bs=32k 25000+0 records in 25000+0 records out 819200000 bytes transferred in 1.037108 secs (789888848 bytes/sec) These are my numbers, but the box is not configured to be benchmarked and is a P4/3.0 GHz, HTT enabled, SMP kernel (most recent RELENG_6) with SCHED_ULE enabled. HD interface is ATA100, slightly aged, I guess ... Regards, Oliver
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