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.
Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
Index: vsyscall/arch/x86/kvm/x86.c
===================================================================
--- vsyscall.orig/arch/x86/kvm/x86.c
+++ vsyscall/arch/x86/kvm/x86.c
@@ -2615,7 +2615,12 @@ void kvm_arch_vcpu_load(struct kvm_vcpu
kvm_x86_ops->write_tsc_offset(vcpu, offset);
vcpu->arch.tsc_catchup = 1;
}
- kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
+ /*
+ * 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);
vcpu->cpu = cpu;
--
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