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
next 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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4F78AD0A.7070904@gmail.com \
--to=hoppetauet@gmail.com \
--cc=fio@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox