KVM: VMX: Avoid unnecessary vcpu_load()/vcpu_put() cycles

By checking if a reschedule is needed, we avoid dropping the vcpu.

[With changes by me, based on Anthony Liguori's observations]

Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 03c0ee7..f535635 100644 (file)
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1590,6 +1590,8 @@ static int set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
 
 void kvm_resched(struct kvm_vcpu *vcpu)
 {
+       if (!need_resched())
+               return;
        vcpu_put(vcpu);
        cond_resched();
        vcpu_load(vcpu);