Re: [PATCH] percpu: add optimized generic percpu accessors

From: Ingo Molnar
Date: Wed Jan 21 2009 - 05:06:36 EST

* Tejun Heo <tj@xxxxxxxxxx> wrote:

> Ingo Molnar wrote:
> > The larger point still remains: the kernel dominantly uses static percpu
> > variables by a margin of 10 to 1, so we cannot just brush away the static
> > percpu variables and must concentrate on optimizing that side with
> > priority. It's nice if the dynamic percpu-alloc side improves as well, of
> > course.
> Well, the infrequent usage of dynamic percpu allocation is in some part
> due to the poor implementation, so it's sort of chicken and egg problem.
> I got into this percpu thing because I wanted a percpu reference count
> which can be dynamically allocated and it sucked.

Sure, but even static percpu sucked very much (it expanded to half a dozen
or more instructions), and dynamic is _more_ complex. Anyway, it's getting
fixed now :-)

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