Re: [PATCH 1/2] scalable rw_mutex

[Oleg Nesterov]

On 05/12, Andi Kleen wrote:
>
> > This also allows us to de-uglify workqueue.c a little bit, it uses
> > a home-grown cpu_populated_map.
> 
> It might be obsolete iff more and more architecture don't use NR_CPUS filled
> possible_map anymore (haven't checked them all to know if it's true or not)
> 
> If not there are a couple of more optimizations that can be done, e.g.
> in networking by converting more code to hotplug notifier.

As for workqueue.c, it is not an optimization. It is a documentation.
For example, if CPU-hotplug use freezer, we can just do

	s/cpu_populated_map/cpu_online_map/

workqueue.c has a hotplug notifier, but we can't migrate work_structs
currently in a race-free manner.

So I vote for your patch in any case.

Oleg.

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