linux-kernel - Re: [RFC][PATCH 0/8] load-balancing and cpu

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Date:	Fri, 4 Sep 2009 09:19:05 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Andreas Herrmann <andreas.herrmann3@....com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org, Gautham R Shenoy <ego@...ibm.com>,
	Balbir Singh <balbir@...ibm.com>
Subject: Re: [RFC][PATCH 0/8] load-balancing and cpu_power -v2

* Andreas Herrmann <andreas.herrmann3@....com> wrote:

> On Tue, Sep 01, 2009 at 10:34:31AM +0200, Peter Zijlstra wrote:
> > A more complete version, one that compiles and mostly works on the
> > simple tests to which it was subjected.
> > 
> > It still lacks integration with APERF/MPERF because that stuff was
> > hidding in some acpi driver instead of placed in arch code for general
> > consumption.. will fix.
> > 
> > Also, SD_SHARE_CPUPOWER seems redundant in the face of sd->level ==
> > SD_LV_SIBLING, should we remove the SD_flag or depricate the level?
> > 
> > Anyway, have at it, poke holes and report issues.
> 
> Tested it (to a certain extend).
> Found no performance degradation (on 1P, 2P, 4P systems). (One could
> think performance might slightly degrade due to more frequent
> __cpu_power updates).

Ok, thanks for doing that, it's really useful - this saved me a day 
of testing and allows me to accelerate these patches and try to 
queue them up in tip:sched today.

Note, we have regressed the load-balancer in recently but its 
inherent complexity makes it pretty hard to fix. We dont max out 
kbuild performance for example - i see this in my distcc builds. 
Would be nice to sort that out too for .32, on top of Peter's 
power-balancing series.

We've got the sched-domains setup simplification suggestions from 
Peter as well, those could be done separately (but are important as 
well, to express more complex hierarchies like Magny-Cours).

	Ingo
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