Commit 4e935e47 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: pmc arbitration



Follow the example set by powerpc and try to play nice with oprofile
and the nmi watchdog.
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarPaul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171024.459968444@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d7d59fb3
...@@ -20,6 +20,7 @@ ...@@ -20,6 +20,7 @@
#include <asm/apic.h> #include <asm/apic.h>
#include <asm/stacktrace.h> #include <asm/stacktrace.h>
#include <asm/nmi.h>
static bool perf_counters_initialized __read_mostly; static bool perf_counters_initialized __read_mostly;
...@@ -172,6 +173,65 @@ x86_perf_counter_update(struct perf_counter *counter, ...@@ -172,6 +173,65 @@ x86_perf_counter_update(struct perf_counter *counter,
atomic64_sub(delta, &hwc->period_left); 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 * Setup the hardware configuration for a given hw_event_type
*/ */
...@@ -179,10 +239,23 @@ static int __hw_perf_counter_init(struct perf_counter *counter) ...@@ -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 perf_counter_hw_event *hw_event = &counter->hw_event;
struct hw_perf_counter *hwc = &counter->hw; struct hw_perf_counter *hwc = &counter->hw;
int err;
if (unlikely(!perf_counters_initialized)) if (unlikely(!perf_counters_initialized))
return -EINVAL; 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: * Generate PMC IRQs:
* (keep 'enabled' bit clear for now) * (keep 'enabled' bit clear for now)
...@@ -230,6 +303,8 @@ static int __hw_perf_counter_init(struct perf_counter *counter) ...@@ -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)); hwc->config |= pmc_ops->event_map(perf_event_id(hw_event));
} }
counter->destroy = hw_perf_counter_destroy;
return 0; return 0;
} }
......
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