Re: [RFC] Extend mwait idle to optimize away IPIs when possible

[Peter Zijlstra]

On Mon, 2012-02-06 at 12:42 -0800, Venkatesh Pallipadi wrote:
> smp_call_function_single and ttwu_queue_remote sends unconditional IPI
> to target CPU. However, if the target CPU is in mwait based idle, we can
> do IPI-less wakeups using the magical powers of monitor-mwait. 

So I was thinking, why not change native_smp_send_reschedule() and
native_send_call_func_single_ipi() and keep the change entirely inside
the arch?

Ideally its only APIC/idle that know about this detail, the scheduler
(or other consumers) really don't care about how the other cpu comes to
run the callback.

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