perf_counter: pmc arbitration (4e935e47) · Commits · 戴 / test

arch/x86/kernel/cpu/perf_counter.c

+75 −0

Original line number	Diff line number	Diff line
		@@ -20,6 +20,7 @@

		#include <asm/apic.h>
		#include <asm/stacktrace.h>
		#include <asm/nmi.h>

		static bool perf_counters_initialized __read_mostly;

		@@ -172,6 +173,65 @@ again:
		atomic64_sub(delta, &hwc->period_left);
		}

		static atomic_t num_counters;
		static DEFINE_MUTEX(pmc_reserve_mutex);

		static bool reserve_pmc_hardware(void)
		{
		int i;

		if (nmi_watchdog == NMI_LOCAL_APIC)
		disable_lapic_nmi_watchdog();

		for (i = 0; i < nr_counters_generic; i++) {
		if (!reserve_perfctr_nmi(pmc_ops->perfctr + i))
		goto perfctr_fail;
		}

		for (i = 0; i < nr_counters_generic; i++) {
		if (!reserve_evntsel_nmi(pmc_ops->eventsel + i))
		goto eventsel_fail;
		}

		return true;

		eventsel_fail:
		for (i--; i >= 0; i--)
		release_evntsel_nmi(pmc_ops->eventsel + i);

		i = nr_counters_generic;

		perfctr_fail:
		for (i--; i >= 0; i--)
		release_perfctr_nmi(pmc_ops->perfctr + i);

		if (nmi_watchdog == NMI_LOCAL_APIC)
		enable_lapic_nmi_watchdog();

		return false;
		}

		static void release_pmc_hardware(void)
		{
		int i;

		for (i = 0; i < nr_counters_generic; i++) {
		release_perfctr_nmi(pmc_ops->perfctr + i);
		release_evntsel_nmi(pmc_ops->eventsel + i);
		}

		if (nmi_watchdog == NMI_LOCAL_APIC)
		enable_lapic_nmi_watchdog();
		}

		static void hw_perf_counter_destroy(struct perf_counter *counter)
		{
		if (atomic_dec_and_mutex_lock(&num_counters, &pmc_reserve_mutex)) {
		release_pmc_hardware();
		mutex_unlock(&pmc_reserve_mutex);
		}
		}

		/*
		* Setup the hardware configuration for a given hw_event_type
		*/
		@@ -179,10 +239,23 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
		{
		struct perf_counter_hw_event *hw_event = &counter->hw_event;
		struct hw_perf_counter *hwc = &counter->hw;
		int err;

		if (unlikely(!perf_counters_initialized))
		return -EINVAL;

		err = 0;
		if (atomic_inc_not_zero(&num_counters)) {
		mutex_lock(&pmc_reserve_mutex);
		if (atomic_read(&num_counters) == 0 && !reserve_pmc_hardware())
		err = -EBUSY;
		else
		atomic_inc(&num_counters);
		mutex_unlock(&pmc_reserve_mutex);
		}
		if (err)
		return err;

		/*
		* Generate PMC IRQs:
		* (keep 'enabled' bit clear for now)
		@@ -230,6 +303,8 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
		hwc->config \|= pmc_ops->event_map(perf_event_id(hw_event));
		}

		counter->destroy = hw_perf_counter_destroy;

		return 0;
		}

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