Re: [patch] improve SMP reschedule and idle routines

[Nick Piggin]

Oleg Nesterov wrote:
> Nick Piggin wrote:
>
> > void default_idle(void)
> > {
> > +	local_irq_enable();
> > +
>
>
> Stupid question. Why is this sti() needed?
>
> Interrupts are enabled in start_secondary() before cpu_idle()
> call, and they can't be disabled after return from schedule().
>
> The same question applies to poll_idle/mwait_idle.

IIRC I tried to do that, but I think I ran into problems with
acpi_processor_idle which looks like it can call the cpu idle
routines with interrupts disabled. I definitely ran into problems
with something.

That should really be cleaned up though (whether we go one way
or the other doesn't matter as much as it being consistent),
I think.

But I wanted to try to keep this patch to a minimum.

--
SUSE Labs, Novell Inc.

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