Hi Peter,

On Wed, 2015-08-26 at 16:32 +0200, Peter Zijlstra wrote:

On Wed, Aug 26, 2015 at 01:21:08PM +0000, Alexey Brodkin wrote:

quoted

Hi Peter,

On Wed, 2015-08-26 at 15:12 +0200, Peter Zijlstra wrote:

quoted

On Mon, Aug 24, 2015 at 05:20:20PM +0300, Alexey Brodkin wrote:

quoted

@@ -295,6 +317,16 @@ static int arc_pmu_add(struct perf_event *event, int flags)
 	}
 
 	write_aux_reg(ARC_REG_PCT_INDEX, idx);
+
+	arc_pmu->act_counter[idx] = event;
+
+	if (is_sampling_event(event)) {
+		/* Mimic full counter overflow as other arches do */
+		write_aux_reg(ARC_REG_PCT_INT_CNTL, (u32)arc_pmu->max_period);
+		write_aux_reg(ARC_REG_PCT_INT_CNTH,
+			      (arc_pmu->max_period >> 32));
+	}
+

pmu::add should call pmu::start when PERF_EF_START, without that it
should not start the counter, only schedule it.

(although currently all pmu::add() calls will have EF_START set)

And that's what we do, don't we?
----------------------->8-----------------------
	if (flags & PERF_EF_START)
		arc_pmu_start(event, PERF_EF_RELOAD);
----------------------->8-----------------------

D'uh indeed! I read that above as enabling it, while what it really does
it simply program the interrupt thresholds.

That's ok.
So do I need to do anything now or both your initial comments today are no longer valid?

-Alexey