From: "Alan D. Brunelle" <Alan.Brunelle@hp.com>
To: linux-btrace@vger.kernel.org
Subject: Re: About the document of "blktrace" and "btt"
Date: Fri, 05 Mar 2010 12:59:47 +0000 [thread overview]
Message-ID: <1267793987.2811.10.camel@cail> (raw)
In-Reply-To: <1267772506.7536.53.camel@linux-92el.site>
On Fri, 2010-03-05 at 15:01 +0800, leon wrote:
> Hi there,
>
> Very appreciated about your "blktrace", "btt" and
> gelato_ICE06apr_blktrace_brunelle_hp.pdf. They are quite powerful!
>
> I am using blktrace-1.0.1-4.3.i586 on kernel 2.6.31.8, but the btt
> output seems a little bit different from that pdf. This doc only
> explained Q2I I2D D2C Q2C
>
> Can anybody help to explain the detail meaning of:
>
> Q2Q
> Q2G
> G2I
> Q2M
> M2D
>
> Or is there any more detailed document about Q, G, I, M, D etc?
>
> Thank you very much
> Leon
Hi Leon -
Check out the btt.pdf generated by "make docs" - in a nutshell, 'Q'
traces indicates entry into the block I/O layer (more or less) so 'Q2Q'
would be the time between entries into the block I/O layer. 'G' is the
'request get' trace - so 'Q2G' shows the time needed to get a request.
'I' is the insert trace - so 'G2I' is how long it then took to find the
right queue spot to put the request on. 'M' is the merge trace - so
'Q2M' indicates how long it took to find & merge an incoming I/O, whilst
'M2D' indicates how long it took for that request to be 'issueD' - sent
down to the underlying device driver.
Regards,
Alan
prev parent reply other threads:[~2010-03-05 12:59 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-05 7:01 About the document of "blktrace" and "btt" leon
2010-03-05 12:59 ` Alan D. Brunelle [this message]
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