To: Andi Kleen <andi@firstfloor.org>
Cc: Peter Zijlstra <peterz@infradead.org>, dipankar@in.ibm.com,
       balbir@linux.vnet.ibm.com, Linux Kernel <linux-kernel@vger.kernel.org>,
       Suresh B Siddha <suresh.b.siddha@intel.com>,
       Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>,
       Ingo Molnar <mingo@elte.hu>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Vatsa <vatsa@linux.vnet.ibm.com>, Gautham R Shenoy <ego@in.ibm.com>
From: Tim Connors <tconnors@astro.swin.edu.au>
Subject: Re: [RFC v1] Tunable sched_mc_power_savings=n
Mail-Copies-To: tconnors@astro.swin.edu.au
In-reply-to: <48641A7D.6080204@firstfloor.org>
References: <20080625191100.GI21892@dirshya.in.ibm.com>
 <87k5gcqpbm.fsf@basil.nowhere.org> <4863AF57.3040005@linux.vnet.ibm.com>
 <4863DB29.1020304@firstfloor.org>
 <20080626185254.GA12416@dirshya.in.ibm.com>
 <4863F93C.9040102@firstfloor.org> <20080626210025.GB26167@in.ibm.com>
 <48640C04.9020600@firstfloor.org>
 <1214516584.12265.10.camel@twins.programming.kicks-ass.net>
 <48641A7D.6080204@firstfloor.org>
Message-ID: <12146282628495-twc@hexane.ssi.swin.edu.au>
Date: Sat, 28 Jun 2008 21:22:27 +1000
User-Agent: slrn/pre0.9.9-111 (Linux)
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1564
Lines: 29

Andi Kleen <andi@firstfloor.org> said on Fri, 27 Jun 2008 00:38:53 +0200:
> Peter Zijlstra wrote:
> 
> >> And your workload manager could just nice processes. It should probably
> >> do that anyways to tell ondemand you don't need full frequency.
> > 
> > Except that I want my nice 19 distcc processes to utilize as much cpu as
> > possible, but just not bother any other stuff I might be doing...
> 
> They already won't do that if you run ondemand and cpufreq. It won't
> crank up the frequency for niced processes.

Shouldn't there be a powernice, just as there is an ionice and a nice?
Just as you don't always want CPU priority and IO priority to be
coupled, Peter has just demonstrated a very good case where you don't
want power and CPU choices to be coupled.  Whether the ondemand
governor of CPUFreq counts a process as wanting the CPU to run at a
higher speed, and these scheduler decisions should be controlled by
powernice.  By default, perhaps a high powernice should equal a high
nice equal to a high ionice, but the user should be able to change
this.  The last thing you want is a distcc process taking up lots of
time, burning more Joules because it runs 10 times longer with only
half the power.  It's not a nice choice between that and running at
nice 0 where it interferes with the user's editing.
--
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/