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Subject[PATCH 1/4] ARCv2: perf: tweak overflow interrupt
Date
Current perf ISR loops thru all 32 counters, checking for each if it
caused the interrupt. Instead only loop thru counters which actually
interrupted (typically 1).

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/kernel/perf_event.c | 24 ++++++++++++++----------
1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/arch/arc/kernel/perf_event.c b/arch/arc/kernel/perf_event.c
index 2ce24e74f879..0eaa132a2c90 100644
--- a/arch/arc/kernel/perf_event.c
+++ b/arch/arc/kernel/perf_event.c
@@ -377,21 +377,22 @@ static irqreturn_t arc_pmu_intr(int irq, void *dev)
struct perf_sample_data data;
struct arc_pmu_cpu *pmu_cpu = this_cpu_ptr(&arc_pmu_cpu);
struct pt_regs *regs;
- int active_ints;
+ unsigned int active_ints;
int idx;

arc_pmu_disable(&arc_pmu->pmu);

active_ints = read_aux_reg(ARC_REG_PCT_INT_ACT);
+ if (!active_ints)
+ goto done;

regs = get_irq_regs();

- for (idx = 0; idx < arc_pmu->n_counters; idx++) {
- struct perf_event *event = pmu_cpu->act_counter[idx];
+ do {
+ struct perf_event *event;
struct hw_perf_event *hwc;

- if (!(active_ints & (1 << idx)))
- continue;
+ idx = __ffs(active_ints);

/* Reset interrupt flag by writing of 1 */
write_aux_reg(ARC_REG_PCT_INT_ACT, 1 << idx);
@@ -404,19 +405,22 @@ static irqreturn_t arc_pmu_intr(int irq, void *dev)
write_aux_reg(ARC_REG_PCT_INT_CTRL,
read_aux_reg(ARC_REG_PCT_INT_CTRL) | (1 << idx));

+ event = pmu_cpu->act_counter[idx];
hwc = &event->hw;

WARN_ON_ONCE(hwc->idx != idx);

arc_perf_event_update(event, &event->hw, event->hw.idx);
perf_sample_data_init(&data, 0, hwc->last_period);
- if (!arc_pmu_event_set_period(event))
- continue;
+ if (arc_pmu_event_set_period(event)) {
+ if (perf_event_overflow(event, &data, regs))
+ arc_pmu_stop(event, 0);
+ }

- if (perf_event_overflow(event, &data, regs))
- arc_pmu_stop(event, 0);
- }
+ active_ints &= ~(1U << idx);
+ } while (active_ints);

+done:
arc_pmu_enable(&arc_pmu->pmu);

return IRQ_HANDLED;
--
2.7.4
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