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    SubjectRe: [PATCH RFC V6 0/11] Paravirtualized ticketlocks
    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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