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From: Hoppetauet <hoppetauet@gmail.com>
To: fio@vger.kernel.org
Subject: Sequential write problems
Date: Sun, 01 Apr 2012 21:31:22 +0200	[thread overview]
Message-ID: <4F78AD0A.7070904@gmail.com> (raw)

Hello

I'm running some benchmarks on virtual machines
I made a script that runs fio N times, with the following job file

[seqwrite]
rw=write
size=${SIZE}
directory=${DIRECTORY}
bs=${BS}
overwrite=1
refill_buffers

The first run gives about 30MB/s, which is what dd tells me is correct 
for the disk at hand
however, from the second to last runs, I get about double that, which 
suggests some sort of caching effect

Is the data that's written to the file not random? I thought 
refill-buffers and overwrite would ensure that

The virtual machines are ubuntu oneiric 11.10, and my fio version is 2.06

Thanks


             reply	other threads:[~2012-04-01 19:31 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-01 19:31 Hoppetauet [this message]
2012-04-02  4:41 ` Sequential write problems Jens Axboe

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