From: Zlatko Calusic <zlatko.calusic@iskon.hr>
To: Rik van Riel <riel@conectiva.com.br>
Cc: Bill Davidsen <davidsen@tmr.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] IO wait accounting
Date: Mon, 13 May 2002 13:45:54 +0200 [thread overview]
Message-ID: <dnvg9sfez1.fsf@magla.zg.iskon.hr> (raw)
In-Reply-To: <Pine.LNX.4.44L.0205121812500.32261-100000@imladris.surriel.com> (Rik van Riel's message of "Sun, 12 May 2002 18:14:01 -0300 (BRT)")
Rik van Riel <riel@conectiva.com.br> writes:
> On Sun, 12 May 2002, Zlatko Calusic wrote:
>> Rik van Riel <riel@conectiva.com.br> writes:
>> >
>> > And should we measure read() waits as well as page faults or
>> > just page faults ?
>>
>> Definitely both.
>
> OK, I'll look at a way to implement these stats so that
> every IO wait counts as iowait time ... preferably in a
> way that doesn't touch the code in too many places ;)
>
>> Somewhere on the web was a nice document explaining
>> how Solaris measures iowait%, I read it few years ago and it was a
>> great stuff (quite nice explanation).
>>
>> I'll try to find it, as it could be helpful.
>
> Please, it would be useful to get our info compatible with
> theirs so sysadmins can read their statistics the same on
> both systems.
>
Yes, that would be nice. Anyway, finding the document I mentioned will
be much harder than I thought. Googling last 15 minutes didn't make
progress. But, I'll keep trying.
Anyway, here is how Aix defines it:
Average percentage of CPU time that the CPUs were idle during which
the system had an outstanding disk I/O request. This value may be
inflated if the actual number of I/O requesting threads is less than
the number of idling processors.
(http://support.bull.de/download/redbooks/Performance/OptimizingYourSystemPerformance.pdf)
Also, Sun has a nice collection of articles at
http://www.sun.com/sun-on-net/itworld/, and among them
http://www.sun.com/sun-on-net/itworld/UIR981001perf.html which speaks
about wait time, but I'm still searching for a more technical document...
--
Zlatko
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next prev parent reply other threads:[~2002-05-13 11:45 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-05-09 0:55 Rik van Riel
2002-05-09 14:30 ` Bill Davidsen
2002-05-09 19:08 ` Rik van Riel
2002-05-12 19:05 ` Zlatko Calusic
2002-05-12 21:14 ` Rik van Riel
2002-05-13 11:40 ` BALBIR SINGH
2002-05-13 13:58 ` Zlatko Calusic
2002-05-13 14:32 ` Rik van Riel
2002-05-13 11:45 ` Zlatko Calusic [this message]
2002-05-13 13:34 ` Rik van Riel
2002-05-13 16:08 ` Bill Davidsen
2002-05-14 19:49 ` Kurtis D. Rader
2002-05-14 21:38 ` Rik van Riel
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