From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raghavendra K T Subject: [PATCH RFC 2/2] kvm: Be courteous to other VMs in overcommitted scenario in PLE handler Date: Fri, 21 Sep 2012 17:30:20 +0530 Message-ID: <20120921120019.27611.66093.sendpatchset@codeblue> References: <20120921115942.27611.67488.sendpatchset@codeblue> Cc: Srikar , "Nikunj A. Dadhania" , KVM , Raghavendra K T , Jiannan Ouyang , chegu vinod , "Andrew M. Theurer" , LKML , Srivatsa Vaddagiri , Gleb Natapov To: Peter Zijlstra , "H. Peter Anvin" , Marcelo Tosatti , Ingo Molnar , Avi Kivity , Rik van Riel Return-path: In-Reply-To: <20120921115942.27611.67488.sendpatchset@codeblue> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org From: Raghavendra K T When PLE handler fails to find a better candidate to yield_to, it goes back and does spin again. This is acceptable when we do not have overcommit. But in overcommitted scenarios (especially when we have large number of small guests), it is better to yield. Reviewed-by: Srikar Dronamraju Signed-off-by: Raghavendra K T --- virt/kvm/kvm_main.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 8323685..713b677 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1660,6 +1660,10 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) } } } + /* In overcommitted cases, yield instead of spinning */ + if (!yielded && rq_nr_running() > 1) + schedule(); + kvm_vcpu_set_in_spin_loop(me, false); /* Ensure vcpu is not eligible during next spinloop */