[PATCH v2 08/35] perf/arm: optimize opencoded atomic find_bit() API

Yury Norov
2023-12-03T19:33:33Z

Switch subsystem to use atomic find_bit() or atomic iterators as
appropriate.

CC: Will Deacon <will@kernel.org>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
drivers/perf/arm-cci.c | 24 ++++++------------------
drivers/perf/arm-ccn.c | 10 ++--------
drivers/perf/arm_dmc620_pmu.c | 9 ++-------
drivers/perf/arm_pmuv3.c | 8 ++------
4 files changed, 12 insertions(+), 39 deletions(-)

diff --git a/drivers/perf/arm-cci.c b/drivers/perf/arm-cci.c
index 61de861eaf91..cb15b4cee5f7 100644
--- a/drivers/perf/arm-cci.c
+++ b/drivers/perf/arm-cci.c
@@ -320,12 +320,9 @@ static int cci400_get_event_idx(struct cci_pmu *cci_pmu,
return CCI400_PMU_CYCLE_CNTR_IDX;
}

- for (idx = CCI400_PMU_CNTR0_IDX; idx <= CCI_PMU_CNTR_LAST(cci_pmu); ++idx)
- if (!test_and_set_bit(idx, hw->used_mask))
- return idx;
-
- /* No counters available */
- return -EAGAIN;
+ idx = find_and_set_next_bit(hw->used_mask, CCI_PMU_CNTR_LAST(cci_pmu) + 1,
+ CCI400_PMU_CNTR0_IDX);
+ return idx < CCI_PMU_CNTR_LAST(cci_pmu) + 1 ? idx : -EAGAIN;
}

static int cci400_validate_hw_event(struct cci_pmu *cci_pmu, unsigned long hw_event)
@@ -802,13 +799,8 @@ static int pmu_get_event_idx(struct cci_pmu_hw_events *hw, struct perf_event *ev
if (cci_pmu->model->get_event_idx)
return cci_pmu->model->get_event_idx(cci_pmu, hw, cci_event);

- /* Generic code to find an unused idx from the mask */
- for (idx = 0; idx <= CCI_PMU_CNTR_LAST(cci_pmu); idx++)
- if (!test_and_set_bit(idx, hw->used_mask))
- return idx;
-
- /* No counters available */
- return -EAGAIN;
+ idx = find_and_set_bit(hw->used_mask, CCI_PMU_CNTR_LAST(cci_pmu) + 1);
+ return idx < CCI_PMU_CNTR_LAST(cci_pmu) + 1 ? idx : -EAGAIN;
}

static int pmu_map_event(struct perf_event *event)
@@ -861,12 +853,8 @@ static void pmu_free_irq(struct cci_pmu *cci_pmu)
{
int i;

- for (i = 0; i < cci_pmu->nr_irqs; i++) {
- if (!test_and_clear_bit(i, &cci_pmu->active_irqs))
- continue;
-
+ for_each_test_and_clear_bit(i, &cci_pmu->active_irqs, cci_pmu->nr_irqs)
free_irq(cci_pmu->irqs[i], cci_pmu);
- }
}

static u32 pmu_read_counter(struct perf_event *event)
diff --git a/drivers/perf/arm-ccn.c b/drivers/perf/arm-ccn.c
index 728d13d8e98a..d657701b1f23 100644
--- a/drivers/perf/arm-ccn.c
+++ b/drivers/perf/arm-ccn.c
@@ -589,15 +589,9 @@ static const struct attribute_group *arm_ccn_pmu_attr_groups[] = {

static int arm_ccn_pmu_alloc_bit(unsigned long *bitmap, unsigned long size)
{
- int bit;
-
- do {
- bit = find_first_zero_bit(bitmap, size);
- if (bit >= size)
- return -EAGAIN;
- } while (test_and_set_bit(bit, bitmap));
+ int bit = find_and_set_bit(bitmap, size);

- return bit;
+ return bit < size ? bit : -EAGAIN;
}

/* All RN-I and RN-D nodes have identical PMUs */
diff --git a/drivers/perf/arm_dmc620_pmu.c b/drivers/perf/arm_dmc620_pmu.c
index 30cea6859574..e41c84dabc3e 100644
--- a/drivers/perf/arm_dmc620_pmu.c
+++ b/drivers/perf/arm_dmc620_pmu.c
@@ -303,13 +303,8 @@ static int dmc620_get_event_idx(struct perf_event *event)
end_idx = DMC620_PMU_MAX_COUNTERS;
}

- for (idx = start_idx; idx < end_idx; ++idx) {
- if (!test_and_set_bit(idx, dmc620_pmu->used_mask))
- return idx;
- }
-
- /* The counters are all in use. */
- return -EAGAIN;
+ idx = find_and_set_next_bit(dmc620_pmu->used_mask, end_idx, start_idx);
+ return idx < end_idx ? idx : -EAGAIN;
}

static inline
diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
index 6ca7be05229c..f046ad9e71f1 100644
--- a/drivers/perf/arm_pmuv3.c
+++ b/drivers/perf/arm_pmuv3.c
@@ -825,13 +825,9 @@ static irqreturn_t armv8pmu_handle_irq(struct arm_pmu *cpu_pmu)
static int armv8pmu_get_single_idx(struct pmu_hw_events *cpuc,
struct arm_pmu *cpu_pmu)
{
- int idx;
+ int idx = find_and_set_next_bit(cpuc->used_mask, cpu_pmu->num_events, ARMV8_IDX_COUNTER0);

- for (idx = ARMV8_IDX_COUNTER0; idx < cpu_pmu->num_events; idx++) {
- if (!test_and_set_bit(idx, cpuc->used_mask))
- return idx;
- }
- return -EAGAIN;
+ return idx < cpu_pmu->num_events ? idx : -EAGAIN;
}

static int armv8pmu_get_chain_idx(struct pmu_hw_events *cpuc,
--
2.40.1