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From: JoaoBR <joao@matik.com.br>
Organization: Infomatik
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Date: Wed, 20 Dec 2006 06:18:12 -0300
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Cc: Mark Kirkwood <markir@paradise.net.nz>
Subject: Re: Cached file read performance with 6.2-PRERELEASE
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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=3D/dev/zero of=3D/tmp/file bs=3D8k count=3D100000      # create f=
ile
> 819200000 bytes transferred in 4.849394 secs (168928321 bytes/sec)
>
> $ dd of=3D/dev/null if=3D/tmp/file bs=3D8k                   # read it
> 819200000 bytes transferred in 2.177922 secs (376138354 bytes/sec)
> $ dd of=3D/dev/null if=3D/tmp/file bs=3D8k                   # read again
> 819200000 bytes transferred in 2.178407 secs (376054620 bytes/sec)
> $ dd of=3D/dev/null if=3D/tmp/file bs=3D32k                  # read it
> 819200000 bytes transferred in 1.801944 secs (454620117 bytes/sec)
>


hum, look my releng_6:

# dd of=3D/dev/null if=3D/c/c1/file bs=3D8k
100000+0 records in
100000+0 records out
819200000 bytes transferred in 1.017492 secs (805116851 bytes/sec)
# dd of=3D/dev/null if=3D/c/c1/file bs=3D8k
100000+0 records in
100000+0 records out
819200000 bytes transferred in 1.015790 secs (806465915 bytes/sec)
# dd of=3D/dev/null if=3D/c/c1/file bs=3D32k
25000+0 records in
25000+0 records out
819200000 bytes transferred in 0.896507 secs (913768635 bytes/sec)

=2D-=20

Jo=E3o







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