Commit 8ccba534 authored by Jing Zhang's avatar Jing Zhang Committed by Paolo Bonzini
Browse files

KVM: stats: Add halt polling related histogram stats 



Add three log histogram stats to record the distribution of time spent
on successful polling, failed polling and VCPU wait.
halt_poll_success_hist: Distribution of spent time for a successful poll.
halt_poll_fail_hist: Distribution of spent time for a failed poll.
halt_wait_hist: Distribution of time a VCPU has spent on waiting.

Signed-off-by: default avatarJing Zhang <jingzhangos@google.com>
Message-Id: <20210802165633.1866976-6-jingzhangos@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 87bcc5fa

arch/powerpc/kvm/book3s_hv.c

+14 −2
Original line number Diff line number Diff line
@@ -4146,17 +4146,29 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc) 
	if (do_sleep) {

		vc->runner->stat.generic.halt_wait_ns +=

			ktime_to_ns(cur) - ktime_to_ns(start_wait);

		KVM_STATS_LOG_HIST_UPDATE(

				vc->runner->stat.generic.halt_wait_hist,

				ktime_to_ns(cur) - ktime_to_ns(start_wait));

		/* Attribute failed poll time */

		if (vc->halt_poll_ns)

		if (vc->halt_poll_ns) {

			vc->runner->stat.generic.halt_poll_fail_ns +=

				ktime_to_ns(start_wait) -

				ktime_to_ns(start_poll);

			KVM_STATS_LOG_HIST_UPDATE(

				vc->runner->stat.generic.halt_poll_fail_hist,

				ktime_to_ns(start_wait) -

				ktime_to_ns(start_poll));

		}

	} else {

		/* Attribute successful poll time */

		if (vc->halt_poll_ns)

		if (vc->halt_poll_ns) {

			vc->runner->stat.generic.halt_poll_success_ns +=

				ktime_to_ns(cur) -

				ktime_to_ns(start_poll);

			KVM_STATS_LOG_HIST_UPDATE(

				vc->runner->stat.generic.halt_poll_success_hist,

				ktime_to_ns(cur) - ktime_to_ns(start_poll));

		}

	}



	/* Adjust poll time */

include/linux/kvm_host.h

+7 −1
Original line number Diff line number Diff line
@@ -1453,7 +1453,13 @@ struct _kvm_stats_desc { 
	STATS_DESC_COUNTER(VCPU_GENERIC, halt_wakeup),			       \

	STATS_DESC_TIME_NSEC(VCPU_GENERIC, halt_poll_success_ns),	       \

	STATS_DESC_TIME_NSEC(VCPU_GENERIC, halt_poll_fail_ns),		       \

	STATS_DESC_TIME_NSEC(VCPU_GENERIC, halt_wait_ns)

	STATS_DESC_TIME_NSEC(VCPU_GENERIC, halt_wait_ns),		       \

	STATS_DESC_LOGHIST_TIME_NSEC(VCPU_GENERIC, halt_poll_success_hist,     \

			HALT_POLL_HIST_COUNT),				       \

	STATS_DESC_LOGHIST_TIME_NSEC(VCPU_GENERIC, halt_poll_fail_hist,	       \

			HALT_POLL_HIST_COUNT),				       \

	STATS_DESC_LOGHIST_TIME_NSEC(VCPU_GENERIC, halt_wait_hist,	       \

			HALT_POLL_HIST_COUNT)



extern struct dentry *kvm_debugfs_dir;

include/linux/kvm_types.h

+5 −0
Original line number Diff line number Diff line
@@ -76,6 +76,8 @@ struct kvm_mmu_memory_cache { 
};

#endif



#define HALT_POLL_HIST_COUNT			32



struct kvm_vm_stat_generic {

	u64 remote_tlb_flush;

};
@@ -88,6 +90,9 @@ struct kvm_vcpu_stat_generic { 
	u64 halt_poll_success_ns;

	u64 halt_poll_fail_ns;

	u64 halt_wait_ns;

	u64 halt_poll_success_hist[HALT_POLL_HIST_COUNT];

	u64 halt_poll_fail_hist[HALT_POLL_HIST_COUNT];

	u64 halt_wait_hist[HALT_POLL_HIST_COUNT];

};



#define KVM_STATS_NAME_SIZE	48

virt/kvm/kvm_main.c

+12 −0
Original line number Diff line number Diff line
@@ -3222,13 +3222,23 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) 
				++vcpu->stat.generic.halt_successful_poll;

				if (!vcpu_valid_wakeup(vcpu))

					++vcpu->stat.generic.halt_poll_invalid;



				KVM_STATS_LOG_HIST_UPDATE(

				      vcpu->stat.generic.halt_poll_success_hist,

				      ktime_to_ns(ktime_get()) -

				      ktime_to_ns(start));

				goto out;

			}

			cpu_relax();

			poll_end = cur = ktime_get();

		} while (kvm_vcpu_can_poll(cur, stop));



		KVM_STATS_LOG_HIST_UPDATE(

				vcpu->stat.generic.halt_poll_fail_hist,

				ktime_to_ns(ktime_get()) - ktime_to_ns(start));

	}





	prepare_to_rcuwait(&vcpu->wait);

	for (;;) {

		set_current_state(TASK_INTERRUPTIBLE);
@@ -3244,6 +3254,8 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) 
	if (waited) {

		vcpu->stat.generic.halt_wait_ns +=

			ktime_to_ns(cur) - ktime_to_ns(poll_end);

		KVM_STATS_LOG_HIST_UPDATE(vcpu->stat.generic.halt_wait_hist,

				ktime_to_ns(cur) - ktime_to_ns(poll_end));

	}

out:

	kvm_arch_vcpu_unblocking(vcpu);