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Commit d98d07ca authored by Marcelo Tosatti's avatar Marcelo Tosatti
Browse files

KVM: x86: update pvclock area conditionally, on cpu migration 



As requested by Glauber, do not update kvmclock area on vcpu->pcpu
migration, in case the host has stable TSC.

This is to reduce cacheline bouncing.

Acked-by: default avatarGlauber Costa <glommer@parallels.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent b48aa97e

arch/x86/kvm/x86.c

+6 −1
Original line number Diff line number Diff line
@@ -2627,6 +2627,11 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) 
			kvm_x86_ops->write_tsc_offset(vcpu, offset);

			vcpu->arch.tsc_catchup = 1;

		}

		/*

		 * On a host with synchronized TSC, there is no need to update

		 * kvmclock on vcpu->cpu migration

		 */

		if (!vcpu->kvm->arch.use_master_clock || vcpu->cpu == -1)

			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);

		if (vcpu->cpu != cpu)

			kvm_migrate_timers(vcpu);