A statistical analysis shows that in most cases when deliverable_irqs()
is called, no interrupts are pending. (see: early exit ratio)
The data was sampled during an iperf3 run over virtio_net
between one guest and the host.
deliverable_irqs()
called = 3145123
by kvm_s390_vcpu_has_irq() = 3005581 (95.56%)
by kvm_arch_vcpu_runnable() = 3005578 (95.56%)
by kvm_s390_handle_wait() = 1219331 (38.76%)
by kvm_vcpu_check_block() = 2943565 (93.59%)
by kvm_cpu_block(1) = 2826431 (89.86%)
by kvm_cpu_block(2) = 117136 (3.72%)
by kvm_arch_dy_runnable() = 0 (0%)
by kvm_arch_setup_async_pf() = 0 (0%)
by handle_stop() = 0 (0%)
by kvm_s390_deliver_pending_interrupt() = 139542 (4.43%)
irqs_delivered = (0:15917 1:61810 2:1 3:0 4:0 x:0)
irqs_pending = (0:15917 1:61722 2:86 3:1 4:0 x:0)
early exit = 3021787 (96.07%)
pending irqs = 123237 (3.91%)
Signed-off-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
---
arch/s390/kvm/interrupt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 028167d6eacd..c34d62b4209e 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -369,7 +369,7 @@ static unsigned long deliverable_irqs(struct kvm_vcpu *vcpu)
unsigned long active_mask;
active_mask = pending_irqs(vcpu);
- if (!active_mask)
+ if (likely(!active_mask))
return 0;
if (psw_extint_disabled(vcpu))
--
2.17.0
