[PATCH 26/29] x86/perfcounters: introduce max_period variable

Robert Richter
2009-04-29T10:59:49Z

In x86 pmus the allowed counter period to programm differs. This
introduces a max_period value and allows the generic implementation
for all models to check the max period.

Signed-off-by: Robert Richter <robert.richter@amd.com>
---
arch/x86/kernel/cpu/perf_counter.c | 20 ++++++++++++--------
1 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index a8a53ab..4b8715b 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -54,6 +54,7 @@ struct x86_pmu {
int num_counters_fixed;
int counter_bits;
u64 counter_mask;
+ u64 max_period;
};

static struct x86_pmu x86_pmu __read_mostly;
@@ -279,14 +280,8 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
hwc->nmi = 1;

hwc->irq_period = hw_event->irq_period;
- /*
- * Intel PMCs cannot be accessed sanely above 32 bit width,
- * so we install an artificial 1<<31 period regardless of
- * the generic counter period:
- */
- if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
- if ((s64)hwc->irq_period <= 0 || hwc->irq_period > 0x7FFFFFFF)
- hwc->irq_period = 0x7FFFFFFF;
+ if ((s64)hwc->irq_period <= 0 || hwc->irq_period > x86_pmu.max_period)
+ hwc->irq_period = x86_pmu.max_period;

atomic64_set(&hwc->period_left, hwc->irq_period);

@@ -910,6 +905,12 @@ static struct x86_pmu intel_pmu = {
.event_map = intel_pmu_event_map,
.raw_event = intel_pmu_raw_event,
.max_events = ARRAY_SIZE(intel_perfmon_event_map),
+ /*
+ * Intel PMCs cannot be accessed sanely above 32 bit width,
+ * so we install an artificial 1<<31 period regardless of
+ * the generic counter period:
+ */
+ .max_period = (1ULL << 31) - 1,
};

static struct x86_pmu amd_pmu = {
@@ -927,6 +928,8 @@ static struct x86_pmu amd_pmu = {
.num_counters = 4,
.counter_bits = 48,
.counter_mask = (1ULL << 48) - 1,
+ /* use highest bit to detect overflow */
+ .max_period = (1ULL << 47) - 1,
};

static int intel_pmu_init(void)
@@ -999,6 +1002,7 @@ void __init init_hw_perf_counters(void)
perf_max_counters = x86_pmu.num_counters;

pr_info("... value mask: %016Lx\n", x86_pmu.counter_mask);
+ pr_info("... max period: %016Lx\n", x86_pmu.max_period);

if (x86_pmu.num_counters_fixed > X86_PMC_MAX_FIXED) {
x86_pmu.num_counters_fixed = X86_PMC_MAX_FIXED;
--
1.6.1.3