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SubjectRe: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq
On Tue, Oct 20, 2015 at 05:40:36PM +0200, Paolo Bonzini wrote:
>
>
> On 20/10/2015 16:00, Peter Zijlstra wrote:
> >> > - prepare_to_wait(&vcpu->wq, &wait, TASK_INTERRUPTIBLE);
> >> > + prepare_to_swait(&vcpu->wq, &wait, TASK_INTERRUPTIBLE);
> >> >
> >> > if (kvm_vcpu_check_block(vcpu) < 0)
> >> > break;
> >> > @@ -2028,7 +2027,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
> >> > schedule();
> >> > }
> >> >
> >> > - finish_wait(&vcpu->wq, &wait);
> >> > + finish_swait(&vcpu->wq, &wait);
> >> > cur = ktime_get();
> >> >
> >> > out:
> > Should we not take this opportunity to get rid of these open-coded wait
> > loops?
>
> I find them way more readable than a 6-argument __wait_event...

I could introduce wait_event_idle_cmd() and be at 3 if you think that
helps.

#define __wait_event_idle_cmd(wq, cond, cmd) \
___wait_event(wq, cond, TASK_IDLE, 0, 0, cmd)

etc..

Its that awkward waited variable that makes it hard to use the 'regular'
2 parameter thing. Although you could of course do horrible things like:

__wait_event_idle(vcpu->wq, ({
bool done = kvm_cpu_check_block(vcpu) < 0;
if (!done)
waited = true;
done;
}));



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