On Fri, Sep 27, 2013 at 01:57:22PM +0200, Peter Zijlstra wrote:
> On Fri, Sep 27, 2013 at 05:14:27PM +0800, Yuanhan Liu wrote:
> > On Wed, Sep 25, 2013 at 09:38:38AM -0700, tip-bot for Peter Zijlstra wrote:
> > > Commit-ID:  f27dde8deef33c9e58027df11ceab2198601d6a6
> > > Gitweb:     http://git.kernel.org/tip/f27dde8deef33c9e58027df11ceab2198601d6a6
> > > Author:     Peter Zijlstra <peterz@infradead.org>
> > > AuthorDate: Wed, 14 Aug 2013 14:55:31 +0200
> > > Committer:  Ingo Molnar <mingo@kernel.org>
> > > CommitDate: Wed, 25 Sep 2013 14:07:49 +0200
> > > 
> > > sched: Add NEED_RESCHED to the preempt_count
> > 
> > Hi Peter,
> > 
> > FYI, here we found a pigz regression by this commit.
> 
> I just can't help myself; but pigs aren't supposed to fly anyway! :-)

Aha!

> > Here is a list all of changed stats by this commit and it's parent 4a2b4b222743bb07fedf985b884550f2ca067ea9:
> > 
> > time.involuntary_context_switches                                          [ 3184       - 4753       ]     [ 5.536e+05  - 5.9042e+05 ]
> > time.voluntary_context_switches                                            [ 84559      - 1.2223e+05 ]     [ 1.1008e+07 - 1.1092e+07 ]
> 
> Gah, that looks like it completely wrecked preemptions.
> 
> What kind of PREEMPT Kconfig options do you use? Or rather; could you
> attach your .config?

Attached.

Thanks,
Fengguang