[PATCH 11/14] KVM: stats: Add stat to detect if vcpu is currently blocking
From: Sean Christopherson <seanjc@google.com>
Date: 2021-09-25 00:56:54
Also in:
kvm, kvmarm, linux-arm-kernel, lkml
Subsystem:
kernel virtual machine (kvm), the rest · Maintainers:
Paolo Bonzini, Linus Torvalds
From: Jing Zhang <redacted> Add a "blocking" stat that userspace can use to detect the case where a vCPU is not being run because of a vCPU/guest action, e.g. HLT or WFS on x86, WFI on arm64, etc... Current guest/host/halt stats don't show this well, e.g. if a guest halts for a long period of time then the vCPU could appear pathologically blocked due to a host condition, when in reality the vCPU has been put into a not-runnable state by the guest. Originally-by: Cannon Matthews [off-list ref] Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Jing Zhang <redacted> [sean: renamed stat to "blocking", massaged changelog] Signed-off-by: Sean Christopherson <seanjc@google.com> --- include/linux/kvm_host.h | 3 ++- include/linux/kvm_types.h | 1 + virt/kvm/kvm_main.c | 2 ++ 3 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 655c2b24db2d..9bb1972e396a 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h@@ -1453,7 +1453,8 @@ struct _kvm_stats_desc { 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) + HALT_POLL_HIST_COUNT), \ + STATS_DESC_ICOUNTER(VCPU_GENERIC, blocking) extern struct dentry *kvm_debugfs_dir;
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index 2237abb93ccd..c4f9257bf32d 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h@@ -94,6 +94,7 @@ struct kvm_vcpu_stat_generic { 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]; + u64 blocking; }; #define KVM_STATS_NAME_SIZE 48
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fe34457530c2..2980d2b88559 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -3208,6 +3208,7 @@ bool kvm_vcpu_block(struct kvm_vcpu *vcpu) { bool waited = false; + vcpu->stat.generic.blocking = 1; kvm_arch_vcpu_blocking(vcpu); prepare_to_rcuwait(&vcpu->wait);
@@ -3223,6 +3224,7 @@ bool kvm_vcpu_block(struct kvm_vcpu *vcpu) finish_rcuwait(&vcpu->wait); kvm_arch_vcpu_unblocking(vcpu); + vcpu->stat.generic.blocking = 0; return waited; }
--
2.33.0.685.g46640cef36-goog