On 08/05/20 20:22, Jon Cargille wrote:
> From: David Matlack <dmatl...@google.com>
>
> 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.
I fixed all the other architectures and queued it, thanks.
Paolo
>
> 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 <dmatl...@google.com>
> Signed-off-by: Jon Cargille <jcarg...@google.com>
> Reviewed-by: Jim Mattson <jmatt...@google.com>
>
> ---
> arch/x86/include/asm/kvm_host.h | 2 ++
> arch/x86/kvm/x86.c | 2 ++
> virt/kvm/kvm_main.c | 20 +++++++++++++++++---
> 3 files changed, 21 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index a239a297be33..3287159ab15b 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1032,6 +1032,8 @@ struct kvm_vcpu_stat {
> u64 irq_injections;
> u64 nmi_injections;
> u64 req_event;
> + u64 halt_poll_success_ns;
> + u64 halt_poll_fail_ns;
> };
>
> struct x86_instruction_info;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 8c0b77ac8dc6..9736d91ce877 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -217,6 +217,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
> VCPU_STAT("nmi_injections", nmi_injections),
> VCPU_STAT("req_event", req_event),
> VCPU_STAT("l1d_flush", l1d_flush),
> + VCPU_STAT( "halt_poll_success_ns", halt_poll_success_ns),
> + VCPU_STAT( "halt_poll_fail_ns", halt_poll_fail_ns),
> VM_STAT("mmu_shadow_zapped", mmu_shadow_zapped),
> VM_STAT("mmu_pte_write", mmu_pte_write),
> VM_STAT("mmu_pte_updated", mmu_pte_updated),
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 33e1eee96f75..348b4a6bde53 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2664,19 +2664,30 @@ static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu)
> return ret;
> }
>
> +static inline void
> +update_halt_poll_stats(struct kvm_vcpu *vcpu, u64 poll_ns, bool waited)
> +{
> +#ifdef CONFIG_X86
> + if (waited)
> + vcpu->stat.halt_poll_fail_ns += poll_ns;
> + else
> + vcpu->stat.halt_poll_success_ns += poll_ns;
> +#endif
> +}
> +
> /*
> * 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;
> DECLARE_SWAITQUEUE(wait);
> 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);
>
> @@ -2692,7 +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));
> }
>
> @@ -2712,6 +2723,9 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
> 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);
>
