Re: [PATCH v7 2/4] perf/smmuv3: Add arm64 smmuv3 pmu driver

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Hi Shameer,

On 26/03/2019 15:17, Shameer Kolothum wrote:
[...]
+static int smmu_pmu_apply_event_filter(struct smmu_pmu *smmu_pmu,
+				       struct perf_event *event, int idx)
+{
+	u32 span, sid;
+	unsigned int num_ctrs = smmu_pmu->num_counters;
+	bool filter_en = !!get_filter_enable(event);
+
+	span = filter_en ? get_filter_span(event) :
+			   SMMU_PMCG_DEFAULT_FILTER_SPAN;
+	sid = filter_en ? get_filter_stream_id(event) :
+			   SMMU_PMCG_DEFAULT_FILTER_SID;
+
+	/* Support individual filter settings */
+	if (!smmu_pmu->global_filter) {
+		smmu_pmu_set_event_filter(event, idx, span, sid);
+		return 0;
+	}
+
+	/* Requested settings same as current global settings*/
+	if (span == smmu_pmu->global_filter_span &&
+	    sid == smmu_pmu->global_filter_sid)
+		return 0;
+
+	if (!bitmap_empty(smmu_pmu->used_counters, num_ctrs))
+		return -EAGAIN;
+
+	if (idx == 0) {
+		smmu_pmu_set_event_filter(event, idx, span, sid);
+		smmu_pmu->global_filter_span = span;
+		smmu_pmu->global_filter_sid = sid;
+		return 0;
+	}

When I suggested dropping the check of idx, I did mean removing it entirely, not just moving it further down ;)

Nothing to worry about though, I'll just leave this here for Will to consider applying on top or squashing.

Thanks,
Robin.

----->8-----
From: Robin Murphy <robin.murphy@xxxxxxx>
Subject: [PATCH] perf/smmuv3: Relax global filter constraint a little

Although the current behaviour of smmu_pmu_get_event_idx() effectively
ensures that the first-allocated counter will be counter 0, there's no
need to strictly enforce that in smmu_pmu_apply_event_filter(). All that
matters is that we only ever touch the global filter settings in
SMMU_PMCG_SMR0 and SMMU_PMCG_EVTYPER0 while no counters are active.

Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
---
 drivers/perf/arm_smmuv3_pmu.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
index 6b3c0ed7ad71..23045ead6de1 100644
--- a/drivers/perf/arm_smmuv3_pmu.c
+++ b/drivers/perf/arm_smmuv3_pmu.c
@@ -286,14 +286,11 @@ static int smmu_pmu_apply_event_filter(struct smmu_pmu *smmu_pmu,
 	if (!bitmap_empty(smmu_pmu->used_counters, num_ctrs))
 		return -EAGAIN;

-	if (idx == 0) {
-		smmu_pmu_set_event_filter(event, idx, span, sid);
-		smmu_pmu->global_filter_span = span;
-		smmu_pmu->global_filter_sid = sid;
-		return 0;
-	}
+	smmu_pmu_set_event_filter(event, 0, span, sid);
+	smmu_pmu->global_filter_span = span;
+	smmu_pmu->global_filter_sid = sid;

-	return -EAGAIN;
+	return 0;
 }

 static int smmu_pmu_get_event_idx(struct smmu_pmu *smmu_pmu,
--
2.20.1.dirty




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