Re: [patch] cpufreq: mark cpufreq_tsc() as core_initcall_sync

From: Linus Torvalds
Date: Thu Nov 16 2006 - 17:22:44 EST




On Thu, 16 Nov 2006, Alan Stern wrote:
> On Thu, 16 Nov 2006, Linus Torvalds wrote:
> >
> > Paul, it would be _really_ nice to have some way to just initialize
> > that SRCU thing statically. This kind of crud is just crazy.
>
> I looked into this back when SRCU was first added. It's essentially
> impossible to do it, because the per-cpu memory allocation & usage APIs
> are completely different for the static and the dynamic cases.

I don't think that's how you'd want to do it.

There's no way to do an initialization of a percpu allocation statically.
That's pretty obvious.

What I'd suggest instead, is to make the allocation dynamic, and make it
inside the srcu functions (kind of like I did now, but I did it at a
higher level).

Doing it at the high level was trivial right now, but we may well end up
hitting this problem again if people start using SRCU more. Right now I
suspect the cpufreq notifier is the only thing that uses SRCU, and it
already showed this problem with SRCU initializers.

So I was more thinking about moving my "one special case high level hack"
down lower, down to the SRCU level, so that we'll never see _more_ of
those horrible hacks. We'll still have the hacky thing, but at least it
will be limited to a single place - the SRCU code itself.

Linus
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