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


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