kvm: Record the preemption status of vcpus using preempt notifiers (3a08a8f9) · Commits · 戴 / test

Note that we mark as preempted only when vcpu's task state was Running during preemption. Thanks Jiannan, Avi for preemption notifier ideas. Thanks Gleb, PeterZ for their precious suggestions. Thanks Srikar for an idea on avoiding rcu lock while checking task state that improved overcommit numbers. Reviewed-by:

Chegu Vinod <chegu_vinod@hp.com> Reviewed-by:

Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by:

Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Signed-off-by:

Gleb Natapov <gleb@redhat.com>

include/linux/kvm_host.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -253,6 +253,7 @@ struct kvm_vcpu {
		bool dy_eligible;
		} spin_loop;
		#endif
		bool preempted;
		struct kvm_vcpu_arch arch;
		};

virt/kvm/kvm_main.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -244,6 +244,7 @@ int kvm_vcpu_init(struct kvm_vcpu vcpu, struct kvm kvm, unsigned id)

		kvm_vcpu_set_in_spin_loop(vcpu, false);
		kvm_vcpu_set_dy_eligible(vcpu, false);
		vcpu->preempted = false;

		r = kvm_arch_vcpu_init(vcpu);
		if (r < 0)
		@@ -2880,6 +2881,8 @@ struct kvm_vcpu preempt_notifier_to_vcpu(struct preempt_notifier pn)
		static void kvm_sched_in(struct preempt_notifier *pn, int cpu)
		{
		struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);
		if (vcpu->preempted)
		vcpu->preempted = false;

		kvm_arch_vcpu_load(vcpu, cpu);
		}
		@@ -2889,6 +2892,8 @@ static void kvm_sched_out(struct preempt_notifier *pn,
		{
		struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);

		if (current->state == TASK_RUNNING)
		vcpu->preempted = true;
		kvm_arch_vcpu_put(vcpu);
		}

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