Re: [PATCH V2 RFC 2/3] kvm: Handle yield_to failure return code for potential undercommit case

[Avi Kivity <avi@redhat.com>]

On 10/31/2012 03:15 PM, Raghavendra K T wrote:
> On 10/31/2012 06:11 PM, Raghavendra K T wrote:
>> On 10/31/2012 06:08 PM, Avi Kivity wrote:
>>> On 10/29/2012 04:07 PM, Raghavendra K T wrote:
>>>> From: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
>>>>
>>>> Also we do not update last boosted vcpu in failure cases.
>>>>
>>>>   #endif
>>>> +
>>>>   void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>>>>   {
>>>>       struct kvm *kvm = me->kvm;
>>>> @@ -1727,11 +1727,12 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>>>>                   continue;
>>>>               if (!kvm_vcpu_eligible_for_directed_yield(vcpu))
>>>>                   continue;
>>>> -            if (kvm_vcpu_yield_to(vcpu)) {
>>>> +
>>>> +            yielded = kvm_vcpu_yield_to(vcpu);
>>>> +            if (yielded > 0)
>>>>                   kvm->last_boosted_vcpu = i;
>>>> -                yielded = 1;
>>>> +            if (yielded)
>>>>                   break;
>>>> -            }
>>>>           }
>>>
>>> If yielded == -ESRCH, should we not try to yield to another vcpu?
>>>
>>
>>   Yes. plan is to abort the iteration. since it means we are mostly
>> undercommitted.
> 
> Sorry if it was ambiguous. I wanted to say we do not want to continue
> yield to another vcpu..
> 


Why not?  We found that this particular vcpu is running and therefore
likely not a lock holder.  That says nothing about other vcpus.  The
next in line might be runnable-but-not-running on another runqueue.


-- 
error compiling committee.c: too many arguments to function