From: Wanpeng Li <[email protected]> To analyze some performance issues with lock contention and scheduling, it is nice to know when directed yield are successful or failing.
Signed-off-by: Wanpeng Li <[email protected]> --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/x86.c | 26 ++++++++++++++++++++------ 2 files changed, 22 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 44f8930..157bcaa 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1126,6 +1126,8 @@ struct kvm_vcpu_stat { u64 halt_poll_success_ns; u64 halt_poll_fail_ns; u64 nested_run; + u64 yield_directed; + u64 yield_directed_ignore; }; struct x86_instruction_info; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 16fb395..3b475cd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -246,6 +246,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { VCPU_STAT("halt_poll_success_ns", halt_poll_success_ns), VCPU_STAT("halt_poll_fail_ns", halt_poll_fail_ns), VCPU_STAT("nested_run", nested_run), + VCPU_STAT("yield_directed", yield_directed), + VCPU_STAT("yield_directed_ignore", yield_directed_ignore), VM_STAT("mmu_shadow_zapped", mmu_shadow_zapped), VM_STAT("mmu_pte_write", mmu_pte_write), VM_STAT("mmu_pde_zapped", mmu_pde_zapped), @@ -8211,21 +8213,33 @@ void kvm_apicv_init(struct kvm *kvm, bool enable) } EXPORT_SYMBOL_GPL(kvm_apicv_init); -static void kvm_sched_yield(struct kvm *kvm, unsigned long dest_id) +static void kvm_sched_yield(struct kvm_vcpu *vcpu, unsigned long dest_id) { struct kvm_vcpu *target = NULL; struct kvm_apic_map *map; + vcpu->stat.yield_directed++; + rcu_read_lock(); - map = rcu_dereference(kvm->arch.apic_map); + map = rcu_dereference(vcpu->kvm->arch.apic_map); if (likely(map) && dest_id <= map->max_apic_id && map->phys_map[dest_id]) target = map->phys_map[dest_id]->vcpu; rcu_read_unlock(); + if (!target) + goto no_yield; + + if (!READ_ONCE(target->ready)) + goto no_yield; - if (target && READ_ONCE(target->ready)) - kvm_vcpu_yield_to(target); + if (kvm_vcpu_yield_to(target) <= 0) + goto no_yield; + return; + +no_yield: + vcpu->stat.yield_directed_ignore++; + return; } int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) @@ -8272,7 +8286,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) break; kvm_pv_kick_cpu_op(vcpu->kvm, a0, a1); - kvm_sched_yield(vcpu->kvm, a1); + kvm_sched_yield(vcpu, a1); ret = 0; break; #ifdef CONFIG_X86_64 @@ -8290,7 +8304,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) if (!guest_pv_has(vcpu, KVM_FEATURE_PV_SCHED_YIELD)) break; - kvm_sched_yield(vcpu->kvm, a0); + kvm_sched_yield(vcpu, a0); ret = 0; break; default: -- 2.7.4
