[PATCH] cpuidle: Enable hpet broadcast by default (RE: [Xen-devel] Time goes backwards in dom0 in xen-unstable)

["Wei, Gang" <gang.wei@xxxxxxxxx>]

cpuidle: Enable hpet broadcast by default

And stop legacy hpet broadcast and limit max C-state to shallower state if RTC 
interrupts are enabled.

Signed-off-by: Wei Gang <gang.wei@xxxxxxxxx>
Signed-off-by: Tian Kevin <kevin.tian@xxxxxxxxx>

On Wednesday, April 15, 2009 5:19 PM, Keir Fraser wrote:
> On 15/04/2009 08:51, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
> 
>> We revised our plan here, after realizing not-negligible effort to
>> enable RTC emulation. Instead we want to turn to an alternative
>> that hpet broadcast is always enabled once available (current
>> situation is to always give up if no MSI delivery support), and
>> then disable it on the fly (disable HPET interrupt and reduce
>> max_cstate to a level not requiring broadcast) once detecting
>> user trying to enable UIE/PIE/AIE on RTC. That way is far
>> simpler and makes cpuidle really available on most platforms
>> with HPET (true for most with VT support), in the meantime
>> not breaking occasional usage on RTC interrupt.
>> 
>> Will you accept such patch which handles mostly about policy? :-)
>> We'll try to send it out today.
> 
> It's got a better chance than RTC emulation. I'll certainly consider it.
> 
>  -- Keir
> 
> 
> 
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Attachment: cpuidle_rtc_mitigation.patch
Description: cpuidle_rtc_mitigation.patch

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