Date: Wed, 20 Dec 2006 06:18:12 -0300 From: JoaoBR <joao@matik.com.br> To: freebsd-stable@freebsd.org Cc: Mark Kirkwood <markir@paradise.net.nz> Subject: Re: Cached file read performance with 6.2-PRERELEASE Message-ID: <200612200618.12826.joao@matik.com.br> In-Reply-To: <45888C68.10305@paradise.net.nz> References: <45888C68.10305@paradise.net.nz>
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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) > > $ dd of=/dev/null if=/tmp/file bs=8k # read it > 819200000 bytes transferred in 2.177922 secs (376138354 bytes/sec) > $ dd of=/dev/null if=/tmp/file bs=8k # read again > 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) > hum, look my releng_6: # dd of=/dev/null if=/c/c1/file bs=8k 100000+0 records in 100000+0 records out 819200000 bytes transferred in 1.017492 secs (805116851 bytes/sec) # dd of=/dev/null if=/c/c1/file bs=8k 100000+0 records in 100000+0 records out 819200000 bytes transferred in 1.015790 secs (806465915 bytes/sec) # dd of=/dev/null if=/c/c1/file bs=32k 25000+0 records in 25000+0 records out 819200000 bytes transferred in 0.896507 secs (913768635 bytes/sec) -- Joćo A mensagem foi scaneada pelo sistema de e-mail e pode ser considerada segura. Service fornecido pelo Datacenter Matik https://datacenter.matik.com.br
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