lkml.org 
[lkml]   [2010]   [Apr]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 7/7] ondemand: Solve the big performance issue with ondemand during disk IO
On Mon, 19 Apr 2010 10:29:47 +0200
Éric Piel <eric.piel@tremplin-utc.net> wrote:
> >
> > The problem and fix are both verified with the "perf timechar" tool.
> Hi,
> I don't doubt that keeping the cpu full frequency during IO can
> improve some specific workloads, however in your log message you
> don't explain how much we are loosing.

first of all, it's so bad that people will just turn the whole power
management off... at which point fixing the really bad bug is actually
quite a win

>
> How much more energy is consumed when doing a "updatedb" or "find /" ?

on the machines I used this on (Core i7's) it's actually hardly
measurable. All CPUs I have access to turn the voltage entirely off
during idle, so while the frequency is higher, if you're mostly IO
bound, it's only for very short durations... while still being mostly
"off".

--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2010-04-19 15:43    [W:0.136 / U:2.228 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site