From: Jay Han <jayhan258@gmail.com>
To: Vincent Fu <vincentfu@gmail.com>
Cc: fio@vger.kernel.org
Subject: Re: Clat calculation
Date: Thu, 21 Sep 2023 11:43:36 -0600 [thread overview]
Message-ID: <CAJ3QLKdBxYi0iXXHaBJ+x7uypeU8HSo3zh0ESVWQWSPD_hFrnA@mail.gmail.com> (raw)
In-Reply-To: <d210f947-6457-f46a-45bc-a167e8de330c@gmail.com>
Thank you very much, Vincent!
I guess the difference between FIO clat and the time delta from
blktrace is caused by the start time for clat. What is interesting to
me is that every action combination I tried as the time delta in
blkparse is generally lower than what FIO clat reported.
On Tue, Sep 19, 2023 at 6:38 AM Vincent Fu <vincentfu@gmail.com> wrote:
>
> On 9/18/23 12:54, Jay Han wrote:
> > Hello,
> > I am seeing a stiff delta between the fio clat vs blktrace data and
> > wondering how fio clat is measured in terms of the I/O processing
> > step. In blktrace, I measured the time delta between the complete(C
> > action) and issued(D action) per LBA basis.
> >
> > Can you tell me how fio clat is calculated please?
> >
> > Thank you,
> > Jay.
>
> Here is an extended discussion of fio's latency calculations:
>
> https://github.com/vincentkfu/fio-blog/wiki/How-does-fio-measure-latency
prev parent reply other threads:[~2023-09-21 20:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-18 16:54 Clat calculation Jay Han
2023-09-19 12:38 ` Vincent Fu
2023-09-21 17:43 ` Jay Han [this message]
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