[PATCH v5 02/15] perf jevents metric: Add ability to rewrite metrics in terms of others

Ian Rogers
2023-01-26T23:37:20Z

Add RewriteMetricsInTermsOfOthers that iterates over pairs of names
and expressions trying to replace an expression, within the current
expression, with its name.
---
tools/perf/pmu-events/metric.py | 73 +++++++++++++++++++++++++++-
tools/perf/pmu-events/metric_test.py | 10 ++++
2 files changed, 81 insertions(+), 2 deletions(-)

diff --git a/tools/perf/pmu-events/metric.py b/tools/perf/pmu-events/metric.py
index 2f2fd220e843..77ea6ff98538 100644
--- a/tools/perf/pmu-events/metric.py
+++ b/tools/perf/pmu-events/metric.py
@@ -4,7 +4,7 @@ import ast
import decimal
import json
import re
-from typing import Dict, List, Optional, Set, Union
+from typing import Dict, List, Optional, Set, Tuple, Union

class Expression:
@@ -26,6 +26,9 @@ class Expression:
"""Returns true when two expressions are the same."""
raise NotImplementedError()

+ def Substitute(self, name: str, expression: 'Expression') -> 'Expression':
+ raise NotImplementedError()
+
def __str__(self) -> str:
return self.ToPerfJson()

@@ -186,6 +189,15 @@ class Operator(Expression):
other.lhs) and self.rhs.Equals(other.rhs)
return False

+ def Substitute(self, name: str, expression: Expression) -> Expression:
+ if self.Equals(expression):
+ return Event(name)
+ lhs = self.lhs.Substitute(name, expression)
+ rhs = None
+ if self.rhs:
+ rhs = self.rhs.Substitute(name, expression)
+ return Operator(self.operator, lhs, rhs)
+

class Select(Expression):
"""Represents a select ternary in the parse tree."""
@@ -225,6 +237,14 @@ class Select(Expression):
other.false_val) and self.true_val.Equals(other.true_val)
return False

+ def Substitute(self, name: str, expression: Expression) -> Expression:
+ if self.Equals(expression):
+ return Event(name)
+ true_val = self.true_val.Substitute(name, expression)
+ cond = self.cond.Substitute(name, expression)
+ false_val = self.false_val.Substitute(name, expression)
+ return Select(true_val, cond, false_val)
+

class Function(Expression):
"""A function in an expression like min, max, d_ratio."""
@@ -267,6 +287,15 @@ class Function(Expression):
return result
return False

+ def Substitute(self, name: str, expression: Expression) -> Expression:
+ if self.Equals(expression):
+ return Event(name)
+ lhs = self.lhs.Substitute(name, expression)
+ rhs = None
+ if self.rhs:
+ rhs = self.rhs.Substitute(name, expression)
+ return Function(self.fn, lhs, rhs)
+

def _FixEscapes(s: str) -> str:
s = re.sub(r'([^\\]),', r'\1\\,', s)
@@ -293,6 +322,9 @@ class Event(Expression):
def Equals(self, other: Expression) -> bool:
return isinstance(other, Event) and self.name == other.name

+ def Substitute(self, name: str, expression: Expression) -> Expression:
+ return self
+

class Constant(Expression):
"""A constant within the expression tree."""
@@ -317,6 +349,9 @@ class Constant(Expression):
def Equals(self, other: Expression) -> bool:
return isinstance(other, Constant) and self.value == other.value

+ def Substitute(self, name: str, expression: Expression) -> Expression:
+ return self
+

class Literal(Expression):
"""A runtime literal within the expression tree."""
@@ -336,6 +371,9 @@ class Literal(Expression):
def Equals(self, other: Expression) -> bool:
return isinstance(other, Literal) and self.value == other.value

+ def Substitute(self, name: str, expression: Expression) -> Expression:
+ return self
+

def min(lhs: Union[int, float, Expression], rhs: Union[int, float,
Expression]) -> Function:
@@ -461,6 +499,7 @@ class MetricGroup:

class _RewriteIfExpToSelect(ast.NodeTransformer):
+ """Transformer to convert if-else nodes to Select expressions."""

def visit_IfExp(self, node):
# pylint: disable=invalid-name
@@ -498,7 +537,37 @@ def ParsePerfJson(orig: str) -> Expression:
for kw in keywords:
py = re.sub(rf'Event\(r"{kw}"\)', kw, py)

- parsed = ast.parse(py, mode='eval')
+ try:
+ parsed = ast.parse(py, mode='eval')
+ except SyntaxError as e:
+ raise SyntaxError(f'Parsing expression:\n{orig}') from e
_RewriteIfExpToSelect().visit(parsed)
parsed = ast.fix_missing_locations(parsed)
return _Constify(eval(compile(parsed, orig, 'eval')))
+
+
+def RewriteMetricsInTermsOfOthers(metrics: List[Tuple[str, Expression]]
+ )-> Dict[str, Expression]:
+ """Shorten metrics by rewriting in terms of others.
+
+ Args:
+ metrics (list): pairs of metric names and their expressions.
+ Returns:
+ Dict: mapping from a metric name to a shortened expression.
+ """
+ updates: Dict[str, Expression] = dict()
+ for outer_name, outer_expression in metrics:
+ updated = outer_expression
+ while True:
+ for inner_name, inner_expression in metrics:
+ if inner_name.lower() == outer_name.lower():
+ continue
+ if inner_name in updates:
+ inner_expression = updates[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]):
+ break
+ updates[outer_name] = updated
+ return updates
diff --git a/tools/perf/pmu-events/metric_test.py b/tools/perf/pmu-events/metric_test.py
index 15315d0f716c..ced5998bd827 100644
--- a/tools/perf/pmu-events/metric_test.py
+++ b/tools/perf/pmu-events/metric_test.py
@@ -2,7 +2,9 @@
import unittest
from metric import Constant
from metric import Event
+from metric import Expression
from metric import ParsePerfJson
+from metric import RewriteMetricsInTermsOfOthers

class TestMetricExpressions(unittest.TestCase):
@@ -153,5 +155,13 @@ class TestMetricExpressions(unittest.TestCase):
after = '0 * SLOTS'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)

+ 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')}
+ self.assertEqual(RewriteMetricsInTermsOfOthers(before), after)
+ Expression.__eq__ = None
+
if __name__ == '__main__':
unittest.main()
--
2.39.1.456.gfc5497dd1b-goog