From: Jens Axboe <axboe@kernel.dk>
To: Andrew Davidoff <davidoff@qedmf.net>
Cc: fio@vger.kernel.org
Subject: Re: Understanding bandwidth results
Date: Mon, 1 Jul 2013 11:59:54 +0200 [thread overview]
Message-ID: <20130701095954.GK15088@kernel.dk> (raw)
In-Reply-To: <CAJLXCZSLQ_GcM=v_nn8xKY+4+bBJC5DSqX9cDf58V5Diwm5MQQ@mail.gmail.com>
On Sun, Jun 30 2013, Andrew Davidoff wrote:
> Hi,
>
> In fio output, I see two values for bandwidth that I'd expect to be
> the same, but that are different. For example, in the results from a
> sync randread fileio test:
>
> read : io=182811KB, bw=18279KB/s, iops=18279, runt= 10001msec
> ...
> bw (KB /s): min= 966, max=21410, per=99.59%, avg=18204.94, stdev=5773.57
>
>
> I realize they are close, but why are the values for bw= and avg= not
> the same? I want to make sure I understand if these are not actually
> reporting on the same statistic.
>
> Also, why is per= not 100%, if this job was run with only a single
> thread in a single group?
That's just rounding and imprecise math. Should be fixed up though. It's
calculated in stat.c:show_ddir_status() and I'll be happy to take
patches :-)
--
Jens Axboe
prev parent reply other threads:[~2013-07-01 9:59 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-30 20:46 Understanding bandwidth results Andrew Davidoff
2013-07-01 9:59 ` Jens Axboe [this message]
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=20130701095954.GK15088@kernel.dk \
--to=axboe@kernel.dk \
--cc=davidoff@qedmf.net \
--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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.