perf jevents: Add threshold expressions to Metric

Allow threshold expressions for metrics to be generated.

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Thomas Falcon <thomas.falcon@intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/pmu-events/metric.py

@@ -430,13 +430,15 @@ class Metric:
   expr: Expression
   scale_unit: str
   constraint: MetricConstraint
+  threshold: Optional[Expression]
 
   def __init__(self,
                name: str,
                description: str,
                expr: Expression,
                scale_unit: str,
-               constraint: MetricConstraint = MetricConstraint.GROUPED_EVENTS):
+               constraint: MetricConstraint = MetricConstraint.GROUPED_EVENTS,
+               threshold: Optional[Expression] = None):
     self.name = name
     self.description = description
     self.expr = expr.Simplify()
@@ -447,6 +449,7 @@ class Metric:
     else:
       self.scale_unit = f'1{scale_unit}'
     self.constraint = constraint
+    self.threshold = threshold
     self.groups = set()
 
   def __lt__(self, other):
@@ -473,6 +476,8 @@ class Metric:
     }
     if self.constraint != MetricConstraint.GROUPED_EVENTS:
       result['MetricConstraint'] = self.constraint.name
+    if self.threshold:
+      result['MetricThreshold'] = self.threshold.ToPerfJson()
 
     return result