Don't rewrite metrics across PMUs as the result events likely won't be
found. Identify metrics with a pair of PMU name and metric name.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/pmu-events/jevents.py     |  4 ++--
 tools/perf/pmu-events/metric.py      | 28 +++++++++++++++++-----------
 tools/perf/pmu-events/metric_test.py |  6 +++---
 3 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py
index b18dd2fcbf04..487ff01baf1b 100755
--- a/tools/perf/pmu-events/jevents.py
+++ b/tools/perf/pmu-events/jevents.py
@@ -391,11 +391,11 @@ def read_json_events(path: str, topic: str) -> Sequence[JsonEvent]:
   except BaseException as err:
     print(f"Exception processing {path}")
     raise
-  metrics: list[Tuple[str, metric.Expression]] = []
+  metrics: list[Tuple[str, str, metric.Expression]] = []
   for event in events:
     event.topic = topic
     if event.metric_name and '-' not in event.metric_name:
-      metrics.append((event.metric_name, event.metric_expr))
+      metrics.append((event.pmu, event.metric_name, event.metric_expr))
   updates = metric.RewriteMetricsInTermsOfOthers(metrics)
   if updates:
     for event in events:
diff --git a/tools/perf/pmu-events/metric.py b/tools/perf/pmu-events/metric.py
index 8ec0ba884673..af58b74d1644 100644
--- a/tools/perf/pmu-events/metric.py
+++ b/tools/perf/pmu-events/metric.py
@@ -552,28 +552,34 @@ def ParsePerfJson(orig: str) -> Expression:
   return _Constify(eval(compile(parsed, orig, 'eval')))
 
 
-def RewriteMetricsInTermsOfOthers(metrics: List[Tuple[str, Expression]]
-                                  )-> Dict[str, Expression]:
+def RewriteMetricsInTermsOfOthers(metrics: List[Tuple[str, str, Expression]]
+                                  )-> Dict[Tuple[str, str], Expression]:
   """Shorten metrics by rewriting in terms of others.
 
   Args:
-    metrics (list): pairs of metric names and their expressions.
+    metrics (list): pmus, metric names and their expressions.
   Returns:
-    Dict: mapping from a metric name to a shortened expression.
+    Dict: mapping from a pmu, metric name pair to a shortened expression.
   """
-  updates: Dict[str, Expression] = dict()
-  for outer_name, outer_expression in metrics:
+  updates: Dict[Tuple[str, str], Expression] = dict()
+  for outer_pmu, outer_name, outer_expression in metrics:
+    if outer_pmu is None:
+      outer_pmu = 'cpu'
     updated = outer_expression
     while True:
-      for inner_name, inner_expression in metrics:
+      for inner_pmu, inner_name, inner_expression in metrics:
+        if inner_pmu is None:
+          inner_pmu = 'cpu'
+        if inner_pmu.lower() != outer_pmu.lower():
+          continue
         if inner_name.lower() == outer_name.lower():
           continue
-        if inner_name in updates:
-          inner_expression = updates[inner_name]
+        if (inner_pmu, inner_name) in updates:
+          inner_expression = updates[(inner_pmu, inner_name)]
         updated = updated.Substitute(inner_name, inner_expression)
       if updated.Equals(outer_expression):
         break
-      if outer_name in updates and updated.Equals(updates[outer_name]):
+      if (outer_pmu, outer_name) in updates and updated.Equals(updates[(outer_pmu, outer_name)]):
         break
-      updates[outer_name] = updated
+      updates[(outer_pmu, outer_name)] = updated
   return updates
diff --git a/tools/perf/pmu-events/metric_test.py b/tools/perf/pmu-events/metric_test.py
index 40a3c7d8b2bc..ee22ff43ddd7 100755
--- a/tools/perf/pmu-events/metric_test.py
+++ b/tools/perf/pmu-events/metric_test.py
@@ -158,9 +158,9 @@ class TestMetricExpressions(unittest.TestCase):
 
   def test_RewriteMetricsInTermsOfOthers(self):
     Expression.__eq__ = lambda e1, e2: e1.Equals(e2)
-    before = [('m1', ParsePerfJson('a + b + c + d')),
-              ('m2', ParsePerfJson('a + b + c'))]
-    after = {'m1': ParsePerfJson('m2 + d')}
+    before = [('cpu', 'm1', ParsePerfJson('a + b + c + d')),
+              ('cpu', 'm2', ParsePerfJson('a + b + c'))]
+    after = {('cpu', 'm1'): ParsePerfJson('m2 + d')}
     self.assertEqual(RewriteMetricsInTermsOfOthers(before), after)
     Expression.__eq__ = None
 
-- 
2.40.1.495.gc816e09b53d-goog