Re: 2.6.12-rc6-mm1

Nick Piggin
2005-06-08T03:50:46Z

On Wed, 2005-06-08 at 13:33 +1000, Con Kolivas wrote:
> On Wed, 8 Jun 2005 01:17 pm, Nick Piggin wrote:

> > To start with, it looks like the smp-nice patches are broken. Even if
> > they weren't I think it might be a good idea just to put them on hold
> > until we work out what to do with the other sched patches...
>
> I originally said I'd wait till the sched patches settled down before tackling
> it but it didn't look like that was ever going to happen and broken nice on
> SMP is a real bug biting people now so I figured I should just tackle it
> anyway. I don't mind if we just work on it later though.
>

Well I agree with you that it would be nice to fix it. I
think your approach has good potential, and it is along
the same lines as what I had in mind.

> > Anyway, Con, this is what it is doing on a 64-way Altix running aim7:
> > (compare imbalances, task move rates, wakeup move rates, etc).
>
> Definitely different I agree. As for the performance impact the statistics
> alone don't tell us if they're for good or evil, but we can look at it again
> separately when we tackle smp nice again. It is a real issue for users now,
> though so it would be good if we can have a calmer period in the future to do
> this (smp nice) by itself.
>

True. Fortunately this seems to only come up once a year or so.
Although I guess with the rise and rise of multi threaded and
multi cored CPUs it could become a bigger issue.

> These are the four patches Andrew:
> 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
> sched-smp-nice-bias-busy-queues-on-idle-rebalance.patch
>

Thanks.

> The other HT patch by me is separate and a bugfix so please leave that in.
>

Yep.

Nick

--
SUSE Labs, Novell Inc.

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