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authorSean Christopherson <seanjc@google.com>2021-10-09 05:12:00 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2021-12-08 12:24:48 +0300
commit30c9434717fd27e634a157dcdee286703b1f4891 (patch)
tree9394f3807474a3f1892808948cc71bb132ca77ab /virt/kvm
parent29e72893cec3b0268e19e7857d10bf79843f94dc (diff)
downloadlinux-30c9434717fd27e634a157dcdee286703b1f4891.tar.xz
KVM: Reconcile discrepancies in halt-polling stats
Move the halt-polling "success" and histogram stats update into the dedicated helper to fix a discrepancy where the success/fail "time" stats consider polling successful so long as the wait is avoided, but the main "success" and histogram stats consider polling successful if and only if a wake event was detected by the halt-polling loop. Move halt_attempted_poll to the helper as well so that all the stats are updated in a single location. While it's a bit odd to update the stat well after the fact, practically speaking there's no meaningful advantage to updating before polling. Note, there is a functional change in addition to the success vs. fail change. The histogram updates previously called ktime_get() instead of using "cur". But that change is desirable as it means all the stats are now updated with the same polling time, and avoids the extra ktime_get(), which isn't expensive but isn't free either. Reviewed-by: David Matlack <dmatlack@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009021236.4122790-8-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm')
-rw-r--r--virt/kvm/kvm_main.c35
1 files changed, 16 insertions, 19 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a7f9c313d642..44158a4794d8 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3275,12 +3275,23 @@ out:
static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start,
ktime_t end, bool success)
{
+ struct kvm_vcpu_stat_generic *stats = &vcpu->stat.generic;
u64 poll_ns = ktime_to_ns(ktime_sub(end, start));
- if (success)
- vcpu->stat.generic.halt_poll_success_ns += poll_ns;
- else
- vcpu->stat.generic.halt_poll_fail_ns += poll_ns;
+ ++vcpu->stat.generic.halt_attempted_poll;
+
+ if (success) {
+ ++vcpu->stat.generic.halt_successful_poll;
+
+ if (!vcpu_valid_wakeup(vcpu))
+ ++vcpu->stat.generic.halt_poll_invalid;
+
+ stats->halt_poll_success_ns += poll_ns;
+ KVM_STATS_LOG_HIST_UPDATE(stats->halt_poll_success_hist, poll_ns);
+ } else {
+ stats->halt_poll_fail_ns += poll_ns;
+ KVM_STATS_LOG_HIST_UPDATE(stats->halt_poll_fail_hist, poll_ns);
+ }
}
/*
@@ -3301,30 +3312,16 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
if (do_halt_poll) {
ktime_t stop = ktime_add_ns(ktime_get(), vcpu->halt_poll_ns);
- ++vcpu->stat.generic.halt_attempted_poll;
do {
/*
* This sets KVM_REQ_UNHALT if an interrupt
* arrives.
*/
- if (kvm_vcpu_check_block(vcpu) < 0) {
- ++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));
+ if (kvm_vcpu_check_block(vcpu) < 0)
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));
}