Re: [PATCH 05/13] rcu: Fix unraised IPI to timekeeping CPU

[Peter Zijlstra]

On Wed, Dec 18, 2013 at 03:56:12PM +0100, Frederic Weisbecker wrote:
> Because scheduler_ipi() conditionally calls irq_enter() and irq_exit()
> (I wonder if that's a good idea btw, is that here to deal with spurious
> scheduler IPIs of some sort?)

No its because the traditional scheduler IPI did all the work from the
interrupt return path -- and like the comment in there says, for many of
the IPIs that's still true.

So going through the architectures and making all scheduler_ipi callers
do irq_enter/exit would actually make them slower.
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