Linux Virtualization - Mar 2014 - [PATCH RFC v6 10/11] pvqspinlock, x86: Enable qspinlock PV support for KVM

Il 12/03/2014 19:54, Waiman Long ha scritto:
> @@ -807,8 +889,13 @@ void __init kvm_spinlock_init(void)
>  	if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
>  		return;
>
> +#ifdef CONFIG_QUEUE_SPINLOCK
> +	pv_lock_ops.kick_cpu = kvm_kick_cpu_type;
> +	pv_lock_ops.hibernate = kvm_hibernate;
> +#else
>  	pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(kvm_lock_spinning);
>  	pv_lock_ops.unlock_kick = kvm_unlock_kick;
> +#endif
This should also disable the unfair path.

Paolo

On 03/13/2014 09:59 AM, Paolo Bonzini wrote:
> Il 12/03/2014 19:54, Waiman Long ha scritto:
>> @@ -807,8 +889,13 @@ void __init kvm_spinlock_init(void)
>>      if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
>>          return;
>>
>> +#ifdef CONFIG_QUEUE_SPINLOCK
>> +    pv_lock_ops.kick_cpu = kvm_kick_cpu_type;
>> +    pv_lock_ops.hibernate = kvm_hibernate;
>> +#else
>>      pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(kvm_lock_spinning);
>>      pv_lock_ops.unlock_kick = kvm_unlock_kick;
>> +#endif
>
> This should also disable the unfair path.
>
> Paolo
>
The unfair lock uses a different jump label and does not require any 
special PV ops. There is a separate init function for that.

-Longman

Il 13/03/2014 20:13, Waiman Long ha scritto:
>>>
>>
>> This should also disable the unfair path.
>>
>> Paolo
>>
>
> The unfair lock uses a different jump label and does not require any
> special PV ops. There is a separate init function for that.
Yeah, what I mean is that the patches that enable paravirtualization 
should also take care of decreasing the unfair-lock jump label when 
paravirtualization is enabled.

Paolo