Commit 4c088493 authored by Raghavendra K T's avatar Raghavendra K T Committed by Avi Kivity
Browse files

KVM: Note down when cpu relax intercepted or pause loop exited 



Noting pause loop exited vcpu or cpu relax intercepted helps in
filtering right candidate to yield. Wrong selection of vcpu;
i.e., a vcpu that just did a pl-exit or cpu relax intercepted may
contribute to performance degradation.

Signed-off-by: default avatarRaghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Reviewed-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> # on s390x
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent f2a74347

include/linux/kvm_host.h

+34 −0
Original line number Diff line number Diff line
@@ -183,6 +183,18 @@ struct kvm_vcpu { 
	} async_pf;

#endif



#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT

	/*

	 * Cpu relax intercept or pause loop exit optimization

	 * in_spin_loop: set when a vcpu does a pause loop exit

	 *  or cpu relax intercepted.

	 * dy_eligible: indicates whether vcpu is eligible for directed yield.

	 */

	struct {

		bool in_spin_loop;

		bool dy_eligible;

	} spin_loop;

#endif

	struct kvm_vcpu_arch arch;

};
@@ -898,5 +910,27 @@ static inline bool kvm_check_request(int req, struct kvm_vcpu *vcpu) 
	}

}



#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT



static inline void kvm_vcpu_set_in_spin_loop(struct kvm_vcpu *vcpu, bool val)

{

	vcpu->spin_loop.in_spin_loop = val;

}

static inline void kvm_vcpu_set_dy_eligible(struct kvm_vcpu *vcpu, bool val)

{

	vcpu->spin_loop.dy_eligible = val;

}



#else /* !CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */



static inline void kvm_vcpu_set_in_spin_loop(struct kvm_vcpu *vcpu, bool val)

{

}



static inline void kvm_vcpu_set_dy_eligible(struct kvm_vcpu *vcpu, bool val)

{

}



#endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */

#endif

virt/kvm/kvm_main.c

+5 −0
Original line number Diff line number Diff line
@@ -239,6 +239,9 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id) 
	}

	vcpu->run = page_address(page);



	kvm_vcpu_set_in_spin_loop(vcpu, false);

	kvm_vcpu_set_dy_eligible(vcpu, false);



	r = kvm_arch_vcpu_init(vcpu);

	if (r < 0)

		goto fail_free_run;
@@ -1585,6 +1588,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) 
	int pass;

	int i;



	kvm_vcpu_set_in_spin_loop(me, true);

	/*

	 * We boost the priority of a VCPU that is runnable but not

	 * currently running, because it got preempted by something
@@ -1610,6 +1614,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) 
			}

		}

	}

	kvm_vcpu_set_in_spin_loop(me, false);

}

EXPORT_SYMBOL_GPL(kvm_vcpu_on_spin);

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