Re: [PATCH] x86 idle: repair large-server 50-watt idle-power regression

From: H. Peter Anvin
Date: Thu Dec 19 2013 - 10:56:33 EST


On 12/19/2013 04:22 AM, Ingo Molnar wrote:
>> diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
>> index 92d1206..f80b700 100644
>> --- a/drivers/idle/intel_idle.c
>> +++ b/drivers/idle/intel_idle.c
>> @@ -377,6 +377,9 @@ static int intel_idle(struct cpuidle_device *dev,
>>
>> if (!current_set_polling_and_test()) {
>>
>> + if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))
>> + clflush((void *)&current_thread_info()->flags);
>> +
>> __monitor((void *)&current_thread_info()->flags, 0, 0);
>
> I don't think either of these casts to '(void *)' is needed, both the
> clflush() and __monitor() will take pointers.

__monitor() currently doesn't, which is idiotic.

-hpa

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