Re: [PATCH/RFC] KVM: halt_polling: provide a way to qualify wakeups during poll

[Christian Borntraeger <borntraeger@de.ibm.com>]

On 05/02/2016 01:46 PM, Cornelia Huck wrote:
> On Mon,  2 May 2016 12:42:33 +0200
> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> 
> 
>> @@ -2038,14 +2039,16 @@ out:
>>  		if (block_ns <= vcpu->halt_poll_ns)
>>  			;
>>  		/* we had a long block, shrink polling */
>> -		else if (vcpu->halt_poll_ns && block_ns > halt_poll_ns)
>> +		else if (!vcpu_valid_wakeup(vcpu) ||
>> +			(vcpu->halt_poll_ns && block_ns > halt_poll_ns))
>>  			shrink_halt_poll_ns(vcpu);
>>  		/* we had a short halt and our poll time is too small */
>>  		else if (vcpu->halt_poll_ns < halt_poll_ns &&
>> -			block_ns < halt_poll_ns)
>> +			block_ns < halt_poll_ns && vcpu_valid_wakeup(vcpu))
> 
> Isn't that vcpu_valid_wakeup() check superflous, as we have collected
> all !vcpu_valid_wakeup() cases in the previous if?

Yes, will fix in v2.


> 
>>  			grow_halt_poll_ns(vcpu);
>>  	} else
>>  		vcpu->halt_poll_ns = 0;
>> +	vcpu_reset_wakeup(vcpu);
>>
>>  	trace_kvm_vcpu_wakeup(block_ns, waited);
>>  }
>