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]
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