Re: [PATCH RFC 3/4] Paravirtualized spinlock implementation for KVMguests

[Avi Kivity]

 On 07/26/2010 09:15 AM, Srivatsa Vaddagiri wrote:
> Paravirtual spinlock implementation for KVM guests, based heavily on Xen guest's
> spinlock implementation.
>
> +static void kvm_spin_unlock(struct arch_spinlock *lock)
> +{
> +	struct kvm_spinlock *sl = (struct kvm_spinlock *)lock;
> +
> +	ADD_STATS(released, 1);
> +
> +	smp_wmb();		/* make sure no writes get moved after unlock */
> +	sl->lock = 0;		/* release lock */
> +}

Wait, no wakeup?

So it is a yield, not a sleep.  I'm worried it could seriously impact 
fairness when one non-contending guest (or non-pv) is overcommitted 
together with a spin-yield guest.

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

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