Re: [RFC][PATCH 0/8] load-balancing and cpu_power -v2

From: Ingo Molnar
Date: Fri Sep 04 2009 - 03:19:21 EST

* Andreas Herrmann <andreas.herrmann3@xxxxxxx> 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).

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