Messages in this thread | | | Date | Wed, 20 Jun 2012 22:11:01 -0400 | From | Rik van Riel <> | Subject | Re: [PATCH] kvm: handle last_boosted_vcpu = 0 case |
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On 06/20/2012 04:12 PM, Raghavendra K T wrote: > On 06/20/2012 02:21 AM, Rik van Riel wrote:
>> Please let me know how it goes. > > Yes, have got result today, too tired to summarize. got better > performance result too. will come back again tomorrow morning. > have to post, randomized start point patch also, which I discussed to > know the opinion.
The other person's problem has also gone away with this patch.
Avi, could I convince you to apply this obvious bugfix to kvm.git? :)
>> ====8<==== >> >> If last_boosted_vcpu == 0, then we fall through all test cases and >> may end up with all VCPUs pouncing on vcpu 0. With a large enough >> guest, this can result in enormous runqueue lock contention, which >> can prevent vcpu0 from running, leading to a livelock. >> >> Changing< to<= makes sure we properly handle that case.
>> >> Signed-off-by: Rik van Riel<riel@redhat.com> >> --- >> virt/kvm/kvm_main.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c >> index 7e14068..1da542b 100644 >> --- a/virt/kvm/kvm_main.c >> +++ b/virt/kvm/kvm_main.c >> @@ -1586,7 +1586,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) >> */ >> for (pass = 0; pass< 2&& !yielded; pass++) { >> kvm_for_each_vcpu(i, vcpu, kvm) { >> - if (!pass&& i< last_boosted_vcpu) { >> + if (!pass&& i<= last_boosted_vcpu) { >> i = last_boosted_vcpu; >> continue; >> } else if (pass&& i> last_boosted_vcpu) >> >> >
-- All rights reversed
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