Commit 109a9826 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: Don't redo ktime_get() when calculating halt-polling stop/deadline 



Calculate the halt-polling "stop" time using "start" instead of redoing
ktime_get().  In practice, the numbers involved are in the noise (e.g.,
in the happy case where hardware correctly predicts do_halt_poll and
there are no interrupts, "start" is probably only a few cycles old)
and either approach is perfectly ok.  But it's more precise to count
any extra latency toward the halt-polling time.

Reviewed-by: default avatarDavid Matlack <dmatlack@google.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-17-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c3858335

virt/kvm/kvm_main.c

+1 −1
Original line number Diff line number Diff line
@@ -3343,7 +3343,7 @@ 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(start, vcpu->halt_poll_ns);



		do {

			/*