Re: 2.6.12-rc6-mm1

Ingo Molnar
2005-06-10T07:09:46Z

* 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