From: Yaozu Dong <eddie.dong@intel.com>
Date: Wed, 25 Apr 2007 13:49:19 +0000 (+0300)
Subject: KVM: VMX: Avoid unnecessary vcpu_load()/vcpu_put() cycles
X-Git-Tag: v2.6.22-rc1~1008^2~11
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3fca03653010b8c5fa63b99fc94c78cbfb433d00;p=linux-2.6

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 03c0ee74d7..f5356358ac 100644
--- 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);