Re: [PATCHv3 2/2] powerpc: implement arch_scale_smt_power for Power7

Joel Schopp
2010-01-29T18:34:52Z

> That said, I'm still not entirely convinced I like this usage of
> cpupower, its supposed to be a normalization scale for load-balancing,
> not a placement hook.
>
Even if you do a placement hook you'll need to address it in the load
balancing as well. Consider a single 4 thread SMT core with 4 running
tasks. If 2 of them exit the remaining 2 will need to be load balanced
within the core in a way that takes into account the dynamic nature of
the thread power. This patch does that.
> I'd be much happier with a SD_GROUP_ORDER or something like that, that
> works together with SD_PREFER_SIBLING to pack active tasks to cpus in
> ascending group order.
>
>
I don't see this load-balancing patch as mutually exclusive with a patch
to fix placement. But even if it is a mutually exclusive solution there
is no reason we can't fix things now with this patch and then later take
it out when it's fixed another way. This patch series is
straightforward, non-intrusive, and without it the scheduler is broken
on this processor.