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| author | David Matlack <dmatlack@google.com> | 2020-05-08 11:22:40 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-05-15 12:26:26 -0400 |
| commit | cb953129bfe5c0f2da835a0469930873fb7e71df (patch) | |
| tree | 51bda79e3c12b776f315f12b7a2f1d36fd651534 /virt/kvm | |
| parent | 93dff2fed2fb4a513196b7df05742c6fcdfd5178 (diff) | |
| download | lwn-cb953129bfe5c0f2da835a0469930873fb7e71df.tar.gz lwn-cb953129bfe5c0f2da835a0469930873fb7e71df.zip | |
kvm: add halt-polling cpu usage stats
Two new stats for exposing halt-polling cpu usage:
halt_poll_success_ns
halt_poll_fail_ns
Thus sum of these 2 stats is the total cpu time spent polling. "success"
means the VCPU polled until a virtual interrupt was delivered. "fail"
means the VCPU had to schedule out (either because the maximum poll time
was reached or it needed to yield the CPU).
To avoid touching every arch's kvm_vcpu_stat struct, only update and
export halt-polling cpu usage stats if we're on x86.
Exporting cpu usage as a u64 and in nanoseconds means we will overflow at
~500 years, which seems reasonably large.
Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Jon Cargille <jcargill@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Message-Id: <20200508182240.68440-1-jcargill@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm')
| -rw-r--r-- | virt/kvm/kvm_main.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 11844fad60fd..da6da386b591 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2667,18 +2667,27 @@ out: return ret; } +static inline void +update_halt_poll_stats(struct kvm_vcpu *vcpu, u64 poll_ns, bool waited) +{ + if (waited) + vcpu->stat.halt_poll_fail_ns += poll_ns; + else + vcpu->stat.halt_poll_success_ns += poll_ns; +} + /* * The vCPU has executed a HLT instruction with in-kernel mode enabled. */ void kvm_vcpu_block(struct kvm_vcpu *vcpu) { - ktime_t start, cur; + ktime_t start, cur, poll_end; bool waited = false; u64 block_ns; kvm_arch_vcpu_blocking(vcpu); - start = cur = ktime_get(); + start = cur = poll_end = ktime_get(); if (vcpu->halt_poll_ns && !kvm_arch_no_poll(vcpu)) { ktime_t stop = ktime_add_ns(ktime_get(), vcpu->halt_poll_ns); @@ -2694,7 +2703,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) ++vcpu->stat.halt_poll_invalid; goto out; } - cur = ktime_get(); + poll_end = cur = ktime_get(); } while (single_task_running() && ktime_before(cur, stop)); } @@ -2714,6 +2723,9 @@ out: kvm_arch_vcpu_unblocking(vcpu); block_ns = ktime_to_ns(cur) - ktime_to_ns(start); + update_halt_poll_stats( + vcpu, ktime_to_ns(ktime_sub(poll_end, start)), waited); + if (!kvm_arch_no_poll(vcpu)) { if (!vcpu_valid_wakeup(vcpu)) { shrink_halt_poll_ns(vcpu); |