From 06e48c510aa37f6e791602e6420422ea7071fe94 Mon Sep 17 00:00:00 2001 From: Raghavendra K T Date: Thu, 19 Jul 2012 15:17:52 +0530 Subject: KVM: Choose better candidate for directed yield Currently, on a large vcpu guests, there is a high probability of yielding to the same vcpu who had recently done a pause-loop exit or cpu relax intercepted. Such a yield can lead to the vcpu spinning again and hence degrade the performance. The patchset keeps track of the pause loop exit/cpu relax interception and gives chance to a vcpu which: (a) Has not done pause loop exit or cpu relax intercepted at all (probably he is preempted lock-holder) (b) Was skipped in last iteration because it did pause loop exit or cpu relax intercepted, and probably has become eligible now (next eligible lock holder) Signed-off-by: Raghavendra K T Reviewed-by: Marcelo Tosatti Reviewed-by: Rik van Riel Tested-by: Christian Borntraeger # on s390x Signed-off-by: Avi Kivity --- include/linux/kvm_host.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux/kvm_host.h') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 361b36fe7ecc..74a78d09c454 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -931,6 +931,11 @@ static inline void kvm_vcpu_set_dy_eligible(struct kvm_vcpu *vcpu, bool val) { } +static inline bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu) +{ + return true; +} + #endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */ #endif -- cgit v1.2.3