[PATCH/RFC] KVM: do early exit in kvm_check_request

Christian Borntraeger
2016-09-09T10:10:21Z

By checking vcpu->requests we can do an early exit and allow gcc
to optimize multiple kvm_check_request into one block for the
common case (no requests).

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
include/linux/kvm_host.h | 2 ++
1 file changed, 2 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 1c9c973..b15b460 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1115,6 +1115,8 @@ static inline void kvm_make_request(int req, struct kvm_vcpu *vcpu)

static inline bool kvm_check_request(int req, struct kvm_vcpu *vcpu)
{
+ if (likely(!vcpu->requests))
+ return false;
if (test_bit(req, &vcpu->requests)) {
clear_bit(req, &vcpu->requests);

--
2.5.5