Calculate the halt-polling "stop" time using "cur" instead of redoing
ktime_get(). In the happy case where hardware correctly predicts
do_halt_poll, "cur" is only a few cycles old. And if the branch is
mispredicted, arguably that extra latency should count toward the
halt-polling time.
In all likelihood, the numbers involved are in the noise and either
approach is perfectly ok.
Reviewed-by: David Matlack <dmatlack@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
virt/kvm/kvm_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a36ccdc93a72..481e8178b43d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3272,7 +3272,7 @@ void kvm_vcpu_halt(struct kvm_vcpu *vcpu)
start = cur = poll_end = ktime_get();
if (do_halt_poll) {
- ktime_t stop = ktime_add_ns(ktime_get(), vcpu->halt_poll_ns);
+ ktime_t stop = ktime_add_ns(cur, vcpu->halt_poll_ns);
do {
/*
--
2.33.0.882.g93a45727a2-goog
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