On 03/29/2012 11:33 PM, Raghavendra K T wrote:
On 03/29/2012 03:28 PM, Avi Kivity wrote:
On 03/28/2012 08:21 PM, Raghavendra K T wrote:
I really like below ideas. Thanks for that!.
- from the PLE handler, don't wake up a vcpu that is sleeping because it
is waiting for a kick
How about, adding another pass in the beginning of kvm_vcpu_on_spin()
to check if any vcpu is already kicked. This would almost result in
yield_to(kicked_vcpu). IMO this is also worth trying.
will try above ideas soon.
I have patch something like below in mind to try:
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d3b98b1..5127668 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1608,15 +1608,18 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
* else and called schedule in __vcpu_run. Hopefully that
* VCPU is holding the lock that we need and will release it.
* We approximate round-robin by starting at the last boosted VCPU.
+ * Priority is given to vcpu that are unhalted.
*/
- for (pass = 0; pass < 2 && !yielded; pass++) {
+ for (pass = 0; pass < 3 && !yielded; pass++) {
kvm_for_each_vcpu(i, vcpu, kvm) {
struct task_struct *task = NULL;
struct pid *pid;
- if (!pass && i < last_boosted_vcpu) {
+ if (!pass && !vcpu->pv_unhalted)
+ continue;
+ else if (pass == 1 && i < last_boosted_vcpu) {
i = last_boosted_vcpu;
continue;
- } else if (pass && i > last_boosted_vcpu)
+ } else if (pass == 2 && i > last_boosted_vcpu)
break;
if (vcpu == me)
continue;
--
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