Re: [PATCH v5 08/11] arm-cci: Provide hook for writing to PMU counters

From: Suzuki K. Poulose
Date: Mon Jan 11 2016 - 07:15:04 EST


On 11/01/16 10:54, Mark Rutland wrote:
On Mon, Jan 04, 2016 at 11:54:47AM +0000, Suzuki K. Poulose wrote:

static struct cci_pmu_model cci_pmu_models[];
@@ -846,7 +847,15 @@ static void pmu_write_counter(struct perf_event *event, u32 value)
dev_err(&cci_pmu->plat_device->dev, "Invalid CCI PMU counter %d\n", idx);
return;
}
- __pmu_write_counter(cci_pmu, value, idx);
+
+ if (cci_pmu->model->write_counters) {
+ unsigned long mask[BITS_TO_LONGS(cci_pmu->num_cntrs)];
+
+ memset(mask, 0, BITS_TO_LONGS(cci_pmu->num_cntrs) * sizeof(unsigned long));
+ set_bit(idx, mask);
+ cci_pmu->model->write_counters(cci_pmu, mask, value);
+ } else
+ __pmu_write_counter(cci_pmu, value, idx);
}

It would be much simpler to always log writes here, and only do the real
wirtes in batches when we re-enable the PMU (with appropriate
disable/enable calls in the IRQ handler).

We'd still need special hooks for CCIs which require a special dance to
program them, but all the logic to handle the writes would be in one
place.

This one is only there for the writes from the irq handler. Now that
we have decided to disable pmu there, we could batch this one too.

Cheers
Suzuki