diff options
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.h | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event_intel.c | 22 |
2 files changed, 22 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h index 2ba71ecc244f..176749cca98f 100644 --- a/arch/x86/kernel/cpu/perf_event.h +++ b/arch/x86/kernel/cpu/perf_event.h @@ -134,6 +134,8 @@ enum intel_excl_state_type { struct intel_excl_states { enum intel_excl_state_type init_state[X86_PMC_IDX_MAX]; enum intel_excl_state_type state[X86_PMC_IDX_MAX]; + int num_alloc_cntrs;/* #counters allocated */ + int max_alloc_cntrs;/* max #counters allowed */ bool sched_started; /* true if scheduling has started */ }; diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index 4773ae0b52d0..4187d3f4ed12 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -1897,7 +1897,7 @@ intel_start_scheduling(struct cpu_hw_events *cpuc) xl = &excl_cntrs->states[tid]; xl->sched_started = true; - + xl->num_alloc_cntrs = 0; /* * lock shared state until we are done scheduling * in stop_event_scheduling() @@ -1963,7 +1963,6 @@ intel_get_excl_constraints(struct cpu_hw_events *cpuc, struct perf_event *event, */ if (cpuc->is_fake) return c; - /* * event requires exclusive counter access * across HT threads @@ -1977,6 +1976,18 @@ intel_get_excl_constraints(struct cpu_hw_events *cpuc, struct perf_event *event, xl = &excl_cntrs->states[tid]; xlo = &excl_cntrs->states[o_tid]; + /* + * do not allow scheduling of more than max_alloc_cntrs + * which is set to half the available generic counters. + * this helps avoid counter starvation of sibling thread + * by ensuring at most half the counters cannot be in + * exclusive mode. There is not designated counters for the + * limits. Any N/2 counters can be used. This helps with + * events with specifix counter constraints + */ + if (xl->num_alloc_cntrs++ == xl->max_alloc_cntrs) + return &emptyconstraint; + cx = c; /* @@ -2624,6 +2635,8 @@ static void intel_pmu_cpu_starting(int cpu) cpuc->lbr_sel = &cpuc->shared_regs->regs[EXTRA_REG_LBR]; if (x86_pmu.flags & PMU_FL_EXCL_CNTRS) { + int h = x86_pmu.num_counters >> 1; + for_each_cpu(i, topology_thread_cpumask(cpu)) { struct intel_excl_cntrs *c; @@ -2637,6 +2650,11 @@ static void intel_pmu_cpu_starting(int cpu) } cpuc->excl_cntrs->core_id = core_id; cpuc->excl_cntrs->refcnt++; + /* + * set hard limit to half the number of generic counters + */ + cpuc->excl_cntrs->states[0].max_alloc_cntrs = h; + cpuc->excl_cntrs->states[1].max_alloc_cntrs = h; } } |