Re: 2.6.12-rc6-mm1

[Ingo Molnar <mingo@elte.hu>]

* Martin J. Bligh <mbligh@mbligh.org> wrote:

> > I'm assuming it was the CPU scheduler patches.  There are 36 of them ;)
> 
> Backed them all out ... performance thunks down to earth again, and is 
> actually the best I've seen it ever (probably 250Hz is helping, I used 
> to run 100 in -mjb for better benefit).
> 
> the +5081 item is the one to look at
> http://ftp.kernel.org/pub/linux/kernel/people/mbligh/abat/perf/kernbench.moe.png
> 
> Patch I used was here:
> 
> http://ftp.kernel.org/pub/linux/kernel/people/mbligh/abat/patches/nosched
> 
> But it was just everything under the "CPU scheduler" section of your 
> series file.

we know from Nick's testing that the patches up to and including 
dynamic-sched-domains-ia64-changes.patch are probably OK. So the 
candidates for the regression are:

 sched-implement-nice-support-across-physical-cpus-on-smp.patch
 sched-change_prio_bias_only_if_queued.patch
 sched-account_rt_tasks_in_prio_bias.patch
 consolidate-preempt-options-into-kernel-kconfigpreempt.patch
 enable-preempt_bkl-on-preemptsmp-too.patch
 sched-tweak-idle-thread-setup-semantics.patch
 sched-voluntary-kernel-preemption.patch
 sched-smp-nice-bias-busy-queues-on-idle-rebalance.patch
 sched-task_noninteractive.patch
 sched-run-sched_normal-tasks-with-real-time-tasks-on-smt-siblings.patch

there are two feature patches in this:

 enable-preempt_bkl-on-preemptsmp-too.patch
 sched-voluntary-kernel-preemption.patch

so make sure you have PREEMPT_BKL and PREEMPT_VOLUNTARY disabled.

these ones should not impact your workload's functionality (unless they 
are buggy):

 sched-account_rt_tasks_in_prio_bias.patch
 consolidate-preempt-options-into-kernel-kconfigpreempt.patch
 sched-tweak-idle-thread-setup-semantics.patch
 sched-run-sched_normal-tasks-with-real-time-tasks-on-smt-siblings.patch

and unless you are using separate nice levels, this one shouldnt make a 
difference in theory:

 sched-implement-nice-support-across-physical-cpus-on-smp.patch

which leaves the following 3 likely candidates:

 sched-change_prio_bias_only_if_queued.patch
 sched-smp-nice-bias-busy-queues-on-idle-rebalance.patch
 sched-task_noninteractive.patch

so if you could do a run with all 3 of the above unapplied, that would 
be a good starting point. (But any of the others might be it too, if 
they contain some sort of bug.)

	Ingo