Re: [patch] improve SMP reschedule and idle routines

[Nick Piggin <nickpiggin@yahoo.com.au>]

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.