Thread (40 messages) 40 messages, 3 authors, 2022-08-11

Re: [PATCH v4 13/17] perf pmu-events: Don't assume pmu_event is an array

From: John Garry <hidden>
Date: 2022-08-05 12:56:16
Also in: linux-perf-users, lkml

On 04/08/2022 23:18, Ian Rogers wrote:
Current code assumes that a struct pmu_event can be iterated over
forward until a NULL pmu_event is encountered. This makes it difficult
to refactor pmu_event. Add a loop function taking a callback function
that's passed the struct pmu_event. This way the pmu_event is only
needed for one element and not an entire array.

Switch existing code iterating over the pmu_event arrays to use the new
loop function pmu_events_table_for_each_event.

I find it hard to follow the change from the description. The title is 
"Don't assume pmu_event is an array", but that is rightly what 
pmu_events_table_for_each_event() does.

If I check - for exmaple - pmu_add_cpu_aliases_map(), you just switch it 
over to using pmu_events_table_for_each_event(), which seems resonable. 
So it just seems here that we're refactoring the code, and not changing 
the nature of how we handle pmu_events *.
quoted hunk ↗ jump to hunk
Signed-off-by: Ian Rogers <irogers@google.com>
---
  tools/perf/pmu-events/empty-pmu-events.c |  34 +++--
  tools/perf/pmu-events/jevents.py         |  34 +++--
  tools/perf/pmu-events/pmu-events.h       |   3 +
  tools/perf/tests/pmu-events.c            | 136 +++++++++--------
  tools/perf/util/metricgroup.c            | 181 ++++++++++++++++-------
  tools/perf/util/pmu.c                    |  65 ++++----
  tools/perf/util/s390-sample-raw.c        |  42 ++++--
  7 files changed, 313 insertions(+), 182 deletions(-)
diff --git a/tools/perf/pmu-events/empty-pmu-events.c b/tools/perf/pmu-events/empty-pmu-events.c
index 028f44efe48d..bee1967baa2b 100644
--- a/tools/perf/pmu-events/empty-pmu-events.c
+++ b/tools/perf/pmu-events/empty-pmu-events.c
@@ -247,6 +247,20 @@ static const struct pmu_sys_events pmu_sys_event_tables[] = {
  	},
  };
  
+int pmu_events_table_for_each_event(const struct pmu_event *table, pmu_event_iter_fn fn,
+				    void *data)
+{
+	for (const struct pmu_event *pe = &table[0];
+	     pe->name || pe->metric_group || pe->metric_name;
+	     pe++) {
+		int ret = fn(pe, table, data);
+
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
  const struct pmu_event *perf_pmu__find_table(struct perf_pmu *pmu)
  {
  	const struct pmu_event *table = NULL;
@@ -291,14 +305,10 @@ int pmu_for_each_core_event(pmu_event_iter_fn fn, void *data)
  	for (const struct pmu_events_map *tables = &pmu_events_map[0];
  	     tables->table;
  	     tables++) {
-		for (const struct pmu_event *pe = &tables->table[0];
-		     pe->name || pe->metric_group || pe->metric_name;
-		     pe++) {
-			int ret = fn(pe, &tables->table[0], data);
+		int ret = pmu_events_table_for_each_event(tables->table, fn, data);
  
-			if (ret)
-				return ret;
-		}
+		if (ret)
+			return ret;
  	}
  	return 0;
  }
@@ -319,14 +329,10 @@ int pmu_for_each_sys_event(pmu_event_iter_fn fn, void *data)
  	for (const struct pmu_sys_events *tables = &pmu_sys_event_tables[0];
  	     tables->name;
  	     tables++) {
-		for (const struct pmu_event *pe = &tables->table[0];
-		     pe->name || pe->metric_group || pe->metric_name;
-		     pe++) {
-			int ret = fn(pe, &tables->table[0], data);
+		int ret = pmu_events_table_for_each_event(tables->table, fn, data);
  
-			if (ret)
-				return ret;
-		}
+		if (ret)
+			return ret;
  	}
  	return 0;
  }
diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py
index e976c5e8e80b..365c960202b0 100755
--- a/tools/perf/pmu-events/jevents.py
+++ b/tools/perf/pmu-events/jevents.py
@@ -409,6 +409,20 @@ static const struct pmu_sys_events pmu_sys_event_tables[] = {
  \t},
  };
  
+int pmu_events_table_for_each_event(const struct pmu_event *table, pmu_event_iter_fn fn,
+                                    void *data)
Again we seem to be just duplicating what is in empty-pmu-events.c - can 
we avoid this? another idea (apart from linking in other c files) is for 
empty-pmu-events.c to be generated from jevents.py (like how it was done 
for jevents.c)

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