Date:   Tue, 15 Nov 2022 09:47:59 -0800
From:   Ian Rogers <irogers@...gle.com>
To:     John Garry <john.g.garry@...cle.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Jiri Olsa <jolsa@...nel.org>, Leo Yan <leo.yan@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Sumanth Korikkar <sumanthk@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Re: RFC Re: [PATCH v2] perf jevents: Parse metrics during conversion

On Tue, Nov 15, 2022 at 9:35 AM John Garry <john.g.garry@...cle.com> wrote:
>
> On 15/11/2022 17:26, Ian Rogers wrote:
> > On Thu, Nov 10, 2022 at 10:48 AM Arnaldo Carvalho de Melo
> > <acme@...nel.org> wrote:
> >>
> >> Em Fri, Oct 28, 2022 at 10:57:02AM -0700, Ian Rogers escreveu:
> >>> On Wed, Oct 12, 2022 at 9:42 AM Ian Rogers <irogers@...gle.com> wrote:
> >>>>
> >>>> Currently the 'MetricExpr' json value is passed from the json
> >>>> file to the pmu-events.c. This change introduces an expression
> >>>> tree that is parsed into. The parsing is done largely by using
> >>>> operator overloading and python's 'eval' function. Two advantages
> >>>> in doing this are:
> >>>>
> >>>> 1) Broken metrics fail at compile time rather than relying on
> >>>>     `perf test` to detect. `perf test` remains relevant for checking
> >>>>     event encoding and actual metric use.
> >>>>
> >>>> 2) The conversion to a string from the tree can minimize the
> >>>>     metric's string size, for example, preferring 1e6 over 1000000
> >>>>     and removing unnecessary whitespace. On x86 this reduces the
> >>>>     string size by 2,823bytes (0.06%).
> >>>>
> >>>> In future changes it would be possible to programmatically
> >>>> generate the json expressions (a single line of text and so a
> >>>> pain to write manually) for an architecture using the expression
> >>>> tree. This could avoid copy-pasting metrics for all architecture
> >>>> variants.
> >>>>
> >>>> Signed-off-by: Ian Rogers <irogers@...gle.com>
> >>>
> >>> Ping, PTAL.
> >>
> >> That would be really nice if people working with JSON, metrics, could
> >> take a look at Ian's work and test it with their files, volunteers?
> >
> > Perhaps John could help?
>
> I'll have a look soon. I have to admit that I have not been tracking the
> jevents changes as close as before.
>
> Thanks,
> John

One thing that it is possible to build using this metric code is
metric generation python code like:

# Max number of instruction retired per cycle.
_RETIRED_INSN = 8
cycles = Event("cycles")
ins = Event("instructions")
def Ipc():
  ipc = d_ratio(ins, cycles)
  peak_ratio = d_ratio(ipc, _RETIRED_INSN)
  return MetricGroup("ipc", [
  Metric("ipc", "Instructions per thread cycle (higher is better)",
ipc, "insn/clks"),
  Metric("ipc_percent_of_peak", "How much of peak IPC has been
obtained", peak_ratio, "100%")
])
print(Ipc().toPerfJson())

This can avoid a lot of the copy-paste metric generation we currently
have. As we can parse expressions into metric python code we could
load the metrics from different sources, etc.

This change isn't adding this, just the metric representation
foundation code, with a modest file size win.

Thanks,
Ian

> >
> > Thanks,
> > Ian
> >
> >> - Arnaldo
> >>
> >>> Thanks,
> >>> Ian
> >>>
> >>>> v2. Improvements to type information.
> >>>> ---
> >>>>   tools/perf/pmu-events/Build          |   2 +-
> >>>>   tools/perf/pmu-events/jevents.py     |  11 +-
> >>>>   tools/perf/pmu-events/metric.py      | 466 +++++++++++++++++++++++++++
> >>>>   tools/perf/pmu-events/metric_test.py | 143 ++++++++
> >>>>   4 files changed, 618 insertions(+), 4 deletions(-)
> >>>>   create mode 100644 tools/perf/pmu-events/metric.py
> >>>>   create mode 100644 tools/perf/pmu-events/metric_test.py
> >>>>
> >>>> diff --git a/tools/perf/pmu-events/Build b/tools/perf/pmu-events/Build
> >>>> index 04ef95174660..15b9e8fdbffa 100644
> >>>> --- a/tools/perf/pmu-events/Build
> >>>> +++ b/tools/perf/pmu-events/Build
> >>>> @@ -21,7 +21,7 @@ $(OUTPUT)pmu-events/pmu-events.c: pmu-events/empty-pmu-events.c
> >>>>          $(call rule_mkdir)
> >>>>          $(Q)$(call echo-cmd,gen)cp $< $@
> >>>>   else
> >>>> -$(OUTPUT)pmu-events/pmu-events.c: $(JSON) $(JSON_TEST) $(JEVENTS_PY)
> >>>> +$(OUTPUT)pmu-events/pmu-events.c: $(JSON) $(JSON_TEST) $(JEVENTS_PY) pmu-events/metric.py
> >>>>          $(call rule_mkdir)
> >>>>          $(Q)$(call echo-cmd,gen)$(PYTHON) $(JEVENTS_PY) $(JEVENTS_ARCH) pmu-events/arch $@
> >>>>   endif
> >>>> diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py
> >>>> index 0daa3e007528..81bcbd15c962 100755
> >>>> --- a/tools/perf/pmu-events/jevents.py
> >>>> +++ b/tools/perf/pmu-events/jevents.py
> >>>> @@ -4,6 +4,7 @@
> >>>>   import argparse
> >>>>   import csv
> >>>>   import json
> >>>> +import metric
> >>>>   import os
> >>>>   import sys
> >>>>   from typing import (Callable, Dict, Optional, Sequence, Set, Tuple)
> >>>> @@ -268,9 +269,9 @@ class JsonEvent:
> >>>>       self.metric_name = jd.get('MetricName')
> >>>>       self.metric_group = jd.get('MetricGroup')
> >>>>       self.metric_constraint = jd.get('MetricConstraint')
> >>>> -    self.metric_expr = jd.get('MetricExpr')
> >>>> -    if self.metric_expr:
> >>>> -      self.metric_expr = self.metric_expr.replace('\\', '\\\\')
> >>>> +    self.metric_expr = None
> >>>> +    if 'MetricExpr' in jd:
> >>>> +       self.metric_expr = metric.ParsePerfJson(jd.get('MetricExpr'))
> >>>>       arch_std = jd.get('ArchStdEvent')
> >>>>       if precise and self.desc and '(Precise Event)' not in self.desc:
> >>>>         extra_desc += ' (Must be precise)' if precise == '2' else (' (Precise '
> >>>> @@ -322,6 +323,10 @@ class JsonEvent:
> >>>>       s = ''
> >>>>       for attr in _json_event_attributes:
> >>>>         x = getattr(self, attr)
> >>>> +      if x and attr == 'metric_expr':
> >>>> +        # Convert parsed metric expressions into a string. Slashes
> >>>> +        # must be doubled in the file.
> >>>> +        x = x.ToPerfJson().replace('\\', '\\\\')
> >>>>         s += f'{x}\\000' if x else '\\000'
> >>>>       return s
> >>>>
> >>>> diff --git a/tools/perf/pmu-events/metric.py b/tools/perf/pmu-events/metric.py
> >>>> new file mode 100644
> >>>> index 000000000000..542d13300e80
> >>>> --- /dev/null
> >>>> +++ b/tools/perf/pmu-events/metric.py
> >>>> @@ -0,0 +1,466 @@
> >>>> +# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
> >>>> +"""Parse or generate representations of perf metrics."""
> >>>> +import ast
> >>>> +import decimal
> >>>> +import re
> >>>> +import json
> >>>> +from typing import (Optional, Set, Union)
> >>>> +
> >>>> +class Expression:
> >>>> +  """Abstract base class of elements in a metric expression."""
> >>>> +
> >>>> +  def ToPerfJson(self) -> str:
> >>>> +    """Returns a perf json file encoded representation."""
> >>>> +    raise NotImplementedError()
> >>>> +
> >>>> +  def ToPython(self) -> str:
> >>>> +    """Returns a python expr parseable representation."""
> >>>> +    raise NotImplementedError()
> >>>> +
> >>>> +  def Simplify(self):
> >>>> +    """Returns a simplified version of self."""
> >>>> +    raise NotImplementedError()
> >>>> +
> >>>> +  def Equals(self, other) -> bool:
> >>>> +    """Returns true when two expressions are the same."""
> >>>> +    raise NotImplementedError()
> >>>> +
> >>>> +  def __str__(self) -> str:
> >>>> +    return self.ToPerfJson()
> >>>> +
> >>>> +  def __or__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('|', self, other)
> >>>> +
> >>>> +  def __ror__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('|', other, self)
> >>>> +
> >>>> +  def __xor__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('^', self, other)
> >>>> +
> >>>> +  def __and__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('&', self, other)
> >>>> +
> >>>> +  def __lt__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('<', self, other)
> >>>> +
> >>>> +  def __gt__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('>', self, other)
> >>>> +
> >>>> +  def __add__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('+', self, other)
> >>>> +
> >>>> +  def __radd__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('+', other, self)
> >>>> +
> >>>> +  def __sub__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('-', self, other)
> >>>> +
> >>>> +  def __rsub__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('-', other, self)
> >>>> +
> >>>> +  def __mul__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('*', self, other)
> >>>> +
> >>>> +  def __rmul__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('*', other, self)
> >>>> +
> >>>> +  def __truediv__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('/', self, other)
> >>>> +
> >>>> +  def __rtruediv__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('/', other, self)
> >>>> +
> >>>> +  def __mod__(self, other: Union[int, float, 'Expression']) -> 'Operator':
> >>>> +    return Operator('%', self, other)
> >>>> +
> >>>> +
> >>>> +def _Constify(val: Union[bool, int, float, Expression]) -> Expression:
> >>>> +  """Used to ensure that the nodes in the expression tree are all Expression."""
> >>>> +  if isinstance(val, bool):
> >>>> +    return Constant(1 if val else 0)
> >>>> +  if isinstance(val, int) or isinstance(val, float):
> >>>> +    return Constant(val)
> >>>> +  return val
> >>>> +
> >>>> +
> >>>> +# Simple lookup for operator precedence, used to avoid unnecessary
> >>>> +# brackets. Precedence matches that of python and the simple expression parser.
> >>>> +_PRECEDENCE = {
> >>>> +    '|': 0,
> >>>> +    '^': 1,
> >>>> +    '&': 2,
> >>>> +    '<': 3,
> >>>> +    '>': 3,
> >>>> +    '+': 4,
> >>>> +    '-': 4,
> >>>> +    '*': 5,
> >>>> +    '/': 5,
> >>>> +    '%': 5,
> >>>> +}
> >>>> +
> >>>> +
> >>>> +class Operator(Expression):
> >>>> +  """Represents a binary operator in the parse tree."""
> >>>> +
> >>>> +  def __init__(self, operator: str, lhs: Union[int, float, Expression],
> >>>> +               rhs: Union[int, float, Expression]):
> >>>> +    self.operator = operator
> >>>> +    self.lhs = _Constify(lhs)
> >>>> +    self.rhs = _Constify(rhs)
> >>>> +
> >>>> +  def Bracket(self,
> >>>> +              other: Expression,
> >>>> +              other_str: str,
> >>>> +              rhs: bool = False) -> str:
> >>>> +    """Returns whether to bracket ``other``
> >>>> +
> >>>> +    ``other`` is the lhs or rhs, ``other_str`` is ``other`` in the
> >>>> +    appropriate string from. If ``other`` is an operator then a
> >>>> +    bracket is necessary when this/self operator has higher
> >>>> +    precedence. Consider: '(a + b) * c', ``other_str`` will be 'a +
> >>>> +    b'. A bracket is necessary as without the bracket 'a + b * c' will
> >>>> +    evaluate 'b * c' first. However, '(a * b) + c' doesn't need a
> >>>> +    bracket as 'a * b' will always be evaluated first. For 'a / (b *
> >>>> +    c)' (ie the same precedence level operations) then we add the
> >>>> +    bracket to best match the original input, but not for '(a / b) *
> >>>> +    c' where the bracket is unnecessary.
> >>>> +    """
> >>>> +    if isinstance(other, Operator):
> >>>> +      if _PRECEDENCE.get(self.operator, -1) > _PRECEDENCE.get(
> >>>> +          other.operator, -1):
> >>>> +        return f'({other_str})'
> >>>> +      if rhs and _PRECEDENCE.get(self.operator, -1) == _PRECEDENCE.get(
> >>>> +          other.operator, -1):
> >>>> +        return f'({other_str})'
> >>>> +    return other_str
> >>>> +
> >>>> +  def ToPerfJson(self):
> >>>> +    return f'{self.Bracket(self.lhs, self.lhs.ToPerfJson())} {self.operator} ' \
> >>>> +      f'{self.Bracket(self.rhs, self.rhs.ToPerfJson(), True)}'
> >>>> +
> >>>> +  def ToPython(self):
> >>>> +    return f'{self.Bracket(self.lhs, self.lhs.ToPython())} {self.operator} ' \
> >>>> +      f'{self.Bracket(self.rhs, self.rhs.ToPython(), True)}'
> >>>> +
> >>>> +  def Simplify(self) -> Expression:
> >>>> +    lhs = self.lhs.Simplify()
> >>>> +    rhs = self.rhs.Simplify()
> >>>> +    if isinstance(lhs, Constant) and isinstance(rhs, Constant):
> >>>> +      return Constant(eval(lhs + self.operator + rhs))
> >>>> +
> >>>> +    if isinstance(self.lhs, Constant):
> >>>> +      if (self.operator == '+' or self.operator == '|') and lhs.value == '0':
> >>>> +        return rhs
> >>>> +
> >>>> +      if self.operator == '*' and lhs.value == '0':
> >>>> +        return Constant(0)
> >>>> +
> >>>> +      if self.operator == '*' and lhs.value == '1':
> >>>> +        return rhs
> >>>> +
> >>>> +    if isinstance(rhs, Constant):
> >>>> +      if (self.operator == '+' or self.operator == '|') and rhs.value == '0':
> >>>> +        return lhs
> >>>> +
> >>>> +      if self.operator == '*' and rhs.value == '0':
> >>>> +        return Constant(0)
> >>>> +
> >>>> +      if self.operator == '*' and self.rhs.value == '1':
> >>>> +        return lhs
> >>>> +
> >>>> +    return Operator(self.operator, lhs, rhs)
> >>>> +
> >>>> +  def Equals(self, other: Expression) -> bool:
> >>>> +    if isinstance(other, Operator):
> >>>> +      return self.operator == other.operator and self.lhs.Equals(
> >>>> +          other.lhs) and self.rhs.Equals(other.rhs)
> >>>> +    return False
> >>>> +
> >>>> +class Select(Expression):
> >>>> +  """Represents a select ternary in the parse tree."""
> >>>> +
> >>>> +  def __init__(self, true_val: Union[int, float, Expression],
> >>>> +               cond: Union[int, float, Expression],
> >>>> +               false_val: Union[int, float, Expression]):
> >>>> +    self.true_val = _Constify(true_val)
> >>>> +    self.cond = _Constify(cond)
> >>>> +    self.false_val = _Constify(false_val)
> >>>> +
> >>>> +  def ToPerfJson(self):
> >>>> +    true_str = self.true_val.ToPerfJson()
> >>>> +    cond_str = self.cond.ToPerfJson()
> >>>> +    false_str = self.false_val.ToPerfJson()
> >>>> +    return f'({true_str} if {cond_str} else {false_str})'
> >>>> +
> >>>> +  def ToPython(self):
> >>>> +    return f'Select({self.true_val.ToPython()}, {self.cond.ToPython()}, ' \
> >>>> +      f'{self.false_val.ToPython()})'
> >>>> +
> >>>> +  def Simplify(self) -> Expression:
> >>>> +    cond = self.cond.Simplify()
> >>>> +    true_val = self.true_val.Simplify()
> >>>> +    false_val = self.false_val.Simplify()
> >>>> +    if isinstance(cond, Constant):
> >>>> +      return false_val if cond.value == '0' else true_val
> >>>> +
> >>>> +    if true_val.Equals(false_val):
> >>>> +      return true_val
> >>>> +
> >>>> +    return Select(true_val, cond, false_val)
> >>>> +
> >>>> +  def Equals(self, other: Expression) -> bool:
> >>>> +    if isinstance(other, Select):
> >>>> +      return self.cond.Equals(other.cond) and self.false_val.Equals(
> >>>> +          other.false_val) and self.true_val.Equals(other.true_val)
> >>>> +    return False
> >>>> +
> >>>> +class Function(Expression):
> >>>> +  """A function in an expression like min, max, d_ratio."""
> >>>> +
> >>>> +  def __init__(self,
> >>>> +               fn: str,
> >>>> +               lhs: Union[int, float, Expression],
> >>>> +               rhs: Optional[Union[int, float, Expression]] = None):
> >>>> +    self.fn = fn
> >>>> +    self.lhs = _Constify(lhs)
> >>>> +    self.rhs = _Constify(rhs)
> >>>> +
> >>>> +  def ToPerfJson(self):
> >>>> +    if self.rhs:
> >>>> +      return f'{self.fn}({self.lhs.ToPerfJson()}, {self.rhs.ToPerfJson()})'
> >>>> +    else:
> >>>> +      return f'{self.fn}({self.lhs.ToPerfJson()})'
> >>>> +
> >>>> +  def ToPython(self):
> >>>> +    if self.rhs:
> >>>> +      return f'{self.fn}({self.lhs.ToPython()}, {self.rhs.ToPython()})'
> >>>> +    else:
> >>>> +      return f'{self.fn}({self.lhs.ToPython()})'
> >>>> +
> >>>> +  def Simplify(self) -> Expression:
> >>>> +    lhs = self.lhs.Simplify()
> >>>> +    rhs = self.rhs.Simplify()
> >>>> +    if isinstance(lhs, Constant) and isinstance(rhs, Constant):
> >>>> +      if self.fn == 'd_ratio':
> >>>> +        if rhs.value == '0':
> >>>> +          return Constant(0)
> >>>> +        Constant(eval(f'{lhs} / {rhs}'))
> >>>> +      return Constant(eval(f'{self.fn}({lhs}, {rhs})'))
> >>>> +
> >>>> +    return Function(self.fn, lhs, rhs)
> >>>> +
> >>>> +  def Equals(self, other: Expression) -> bool:
> >>>> +    if isinstance(other, Function):
> >>>> +      return self.fn == other.fn and self.lhs.Equals(
> >>>> +          other.lhs) and self.rhs.Equals(other.rhs)
> >>>> +    return False
> >>>> +
> >>>> +
> >>>> +class Event(Expression):
> >>>> +  """An event in an expression."""
> >>>> +
> >>>> +  def __init__(self, name: str, legacy_name: str = ''):
> >>>> +    self.name = name
> >>>> +    self.legacy_name = legacy_name
> >>>> +
> >>>> +  def ToPerfJson(self):
> >>>> +    result = re.sub('/', '@', self.name)
> >>>> +    return result
> >>>> +
> >>>> +  def ToPython(self):
> >>>> +    return f'Event(r"{self.name}")'
> >>>> +
> >>>> +  def Simplify(self) -> Expression:
> >>>> +    return self
> >>>> +
> >>>> +  def Equals(self, other: Expression) -> bool:
> >>>> +    return isinstance(other, Event) and self.name == other.name
> >>>> +
> >>>> +class Constant(Expression):
> >>>> +  """A constant within the expression tree."""
> >>>> +
> >>>> +  def __init__(self, value: Union[float, str]):
> >>>> +    ctx = decimal.Context()
> >>>> +    ctx.prec = 20
> >>>> +    dec = ctx.create_decimal(repr(value) if isinstance(value, float) else value)
> >>>> +    self.value = dec.normalize().to_eng_string()
> >>>> +    self.value = self.value.replace('+', '')
> >>>> +    self.value = self.value.replace('E', 'e')
> >>>> +
> >>>> +  def ToPerfJson(self):
> >>>> +    return self.value
> >>>> +
> >>>> +  def ToPython(self):
> >>>> +    return f'Constant({self.value})'
> >>>> +
> >>>> +  def Simplify(self) -> Expression:
> >>>> +    return self
> >>>> +
> >>>> +  def Equals(self, other: Expression) -> bool:
> >>>> +    return isinstance(other, Constant) and self.value == other.value
> >>>> +
> >>>> +class Literal(Expression):
> >>>> +  """A runtime literal within the expression tree."""
> >>>> +
> >>>> +  def __init__(self, value: str):
> >>>> +    self.value = value
> >>>> +
> >>>> +  def ToPerfJson(self):
> >>>> +    return self.value
> >>>> +
> >>>> +  def ToPython(self):
> >>>> +    return f'Literal({self.value})'
> >>>> +
> >>>> +  def Simplify(self) -> Expression:
> >>>> +    return self
> >>>> +
> >>>> +  def Equals(self, other: Expression) -> bool:
> >>>> +    return isinstance(other, Literal) and self.value == other.value
> >>>> +
> >>>> +
> >>>> +def min(lhs: Union[int, float, Expression], rhs: Union[int, float,
> >>>> +                                                       Expression]) -> Function:
> >>>> +  return Function('min', lhs, rhs)
> >>>> +
> >>>> +
> >>>> +def max(lhs: Union[int, float, Expression], rhs: Union[int, float,
> >>>> +                                                       Expression]) -> Function:
> >>>> +  return Function('max', lhs, rhs)
> >>>> +
> >>>> +
> >>>> +def d_ratio(lhs: Union[int, float, Expression],
> >>>> +            rhs: Union[int, float, Expression]) -> Function:
> >>>> +  return Function('d_ratio', lhs, rhs)
> >>>> +
> >>>> +
> >>>> +def source_count(event: Event) -> Function:
> >>>> +  return Function('source_count', event)
> >>>> +
> >>>> +class Metric:
> >>>> +  """An individual metric that will specifiable on the perf command line."""
> >>>> +  groups: Set[str]
> >>>> +  expr: Expression
> >>>> +  scale_unit: str
> >>>> +  constraint: bool
> >>>> +
> >>>> +  def __init__(self,
> >>>> +               name: str,
> >>>> +               description: str,
> >>>> +               expr: Expression,
> >>>> +               scale_unit: str,
> >>>> +               constraint: bool = False):
> >>>> +    self.name = name
> >>>> +    self.description = description
> >>>> +    self.expr = expr.Simplify()
> >>>> +    # Workraound valid_only_metric hiding certain metrics based on unit.
> >>>> +    scale_unit = scale_unit.replace('/sec', ' per sec')
> >>>> +    if scale_unit[0].isdigit():
> >>>> +      self.scale_unit = scale_unit
> >>>> +    else:
> >>>> +      self.scale_unit = f'1{scale_unit}'
> >>>> +    self.constraint = constraint
> >>>> +    self.groups = set()
> >>>> +
> >>>> +  def __lt__(self, other):
> >>>> +    """Sort order."""
> >>>> +    return self.name < other.name
> >>>> +
> >>>> +  def AddToMetricGroup(self, group):
> >>>> +    """Callback used when being added to a MetricGroup."""
> >>>> +    self.groups.add(group.name)
> >>>> +
> >>>> +  def Flatten(self) -> set:
> >>>> +    """Return a leaf metric."""
> >>>> +    return set([self])
> >>>> +
> >>>> +  def ToPerfJson(self):
> >>>> +    result = {
> >>>> +        'MetricName': self.name,
> >>>> +        'MetricGroup': ';'.join(sorted(self.groups)),
> >>>> +        'BriefDescription': self.description,
> >>>> +        'MetricExpr': self.expr.ToPerfJson(),
> >>>> +        'ScaleUnit': self.scale_unit
> >>>> +    }
> >>>> +    if self.constraint:
> >>>> +      result['MetricConstraint'] = 'NO_NMI_WATCHDOG'
> >>>> +
> >>>> +    return result
> >>>> +
> >>>> +
> >>>> +class _MetricJsonEncoder(json.JSONEncoder):
> >>>> +  """Special handling for Metric objects."""
> >>>> +
> >>>> +  def default(self, obj):
> >>>> +    if isinstance(obj, Metric):
> >>>> +      return obj.ToPerfJson()
> >>>> +    return json.JSONEncoder.default(self, obj)
> >>>> +
> >>>> +
> >>>> +class MetricGroup:
> >>>> +  """A group of metrics.
> >>>> +
> >>>> +  Metric groups may be specificd on the perf command line, but within
> >>>> +  the json they aren't encoded. Metrics may be in multiple groups
> >>>> +  which can facilitate arrangements similar to trees.
> >>>> +  """
> >>>> +
> >>>> +  def __init__(self, name: str, metric_list: list[Union[Metric,
> >>>> +                                                        'MetricGroup']]):
> >>>> +    self.name = name
> >>>> +    self.metric_list = metric_list
> >>>> +    for metric in metric_list:
> >>>> +      metric.AddToMetricGroup(self)
> >>>> +
> >>>> +  def AddToMetricGroup(self, group):
> >>>> +    """Callback used when a MetricGroup is added into another."""
> >>>> +    for metric in self.metric_list:
> >>>> +      metric.AddToMetricGroup(group)
> >>>> +
> >>>> +  def Flatten(self) -> set:
> >>>> +    """Returns a set of all leaf metrics."""
> >>>> +    result = set()
> >>>> +    for x in self.metric_list:
> >>>> +      result = result.union(x.Flatten())
> >>>> +
> >>>> +    return result
> >>>> +
> >>>> +  def ToPerfJson(self) -> str:
> >>>> +    return json.dumps(sorted(self.Flatten()), indent=2, cls=_MetricJsonEncoder)
> >>>> +
> >>>> +  def __str__(self) -> str:
> >>>> +    return self.ToPerfJson()
> >>>> +
> >>>> +
> >>>> +class _RewriteIfExpToSelect(ast.NodeTransformer):
> >>>> +
> >>>> +  def visit_IfExp(self, node):
> >>>> +    call = ast.Call(
> >>>> +        func=ast.Name(id='Select', ctx=ast.Load()),
> >>>> +        args=[node.body, node.test, node.orelse],
> >>>> +        keywords=[])
> >>>> +    ast.copy_location(call, node.test)
> >>>> +    return call
> >>>> +
> >>>> +
> >>>> +def ParsePerfJson(orig: str) -> Expression:
> >>>> +  """A simple json metric expression decoder.
> >>>> +
> >>>> +  Converts a json encoded metric expression by way of python's ast and
> >>>> +  eval routine. First tokens are mapped to Event calls, then
> >>>> +  accidentally converted keywords or literals are mapped to their
> >>>> +  appropriate calls. Python's ast is used to match if-else that can't
> >>>> +  be handled via operator overloading. Finally the ast is evaluated.
> >>>> +  """
> >>>> +  py = orig.strip()
> >>>> +  py = re.sub(r'([a-zA-Z][^-+/\* \\\(\),]*(?:\\.[^-+/\* \\\(\),]*)*)',
> >>>> +              r'Event(r"\1")', py)
> >>>> +  py = re.sub(r'#Event\(r"([^"]*)"\)', r'Literal("#\1")', py)
> >>>> +  py = re.sub(r'([0-9]+)Event\(r"(e[0-9]+)"\)', r'\1\2', py)
> >>>> +  keywords = ['if', 'else', 'min', 'max', 'd_ratio', 'source_count']
> >>>> +  for kw in keywords:
> >>>> +    py = re.sub(f'Event\(r"{kw}"\)', kw, py)
> >>>> +
> >>>> +  parsed = ast.parse(py, mode='eval')
> >>>> +  _RewriteIfExpToSelect().visit(parsed)
> >>>> +  parsed = ast.fix_missing_locations(parsed)
> >>>> +  return _Constify(eval(compile(parsed, orig, 'eval')))
> >>>> diff --git a/tools/perf/pmu-events/metric_test.py b/tools/perf/pmu-events/metric_test.py
> >>>> new file mode 100644
> >>>> index 000000000000..3909ca773ca1
> >>>> --- /dev/null
> >>>> +++ b/tools/perf/pmu-events/metric_test.py
> >>>> @@ -0,0 +1,143 @@
> >>>> +# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
> >>>> +import unittest
> >>>> +from metric import Constant, Event, ParsePerfJson
> >>>> +
> >>>> +
> >>>> +class TestMetricExpressions(unittest.TestCase):
> >>>> +
> >>>> +  def test_Operators(self):
> >>>> +    a = Event('a')
> >>>> +    b = Event('b')
> >>>> +    self.assertEqual((a | b).ToPerfJson(), 'a | b')
> >>>> +    self.assertEqual((a ^ b).ToPerfJson(), 'a ^ b')
> >>>> +    self.assertEqual((a & b).ToPerfJson(), 'a & b')
> >>>> +    self.assertEqual((a < b).ToPerfJson(), 'a < b')
> >>>> +    self.assertEqual((a > b).ToPerfJson(), 'a > b')
> >>>> +    self.assertEqual((a + b).ToPerfJson(), 'a + b')
> >>>> +    self.assertEqual((a - b).ToPerfJson(), 'a - b')
> >>>> +    self.assertEqual((a * b).ToPerfJson(), 'a * b')
> >>>> +    self.assertEqual((a / b).ToPerfJson(), 'a / b')
> >>>> +    self.assertEqual((a % b).ToPerfJson(), 'a % b')
> >>>> +
> >>>> +  def test_Brackets(self):
> >>>> +    a = Event('a')
> >>>> +    b = Event('b')
> >>>> +    c = Event('c')
> >>>> +    self.assertEqual((a * b + c).ToPerfJson(), 'a * b + c')
> >>>> +    self.assertEqual((a + b * c).ToPerfJson(), 'a + b * c')
> >>>> +    self.assertEqual(((a + a) + a).ToPerfJson(), 'a + a + a')
> >>>> +    self.assertEqual(((a + b) * c).ToPerfJson(), '(a + b) * c')
> >>>> +    self.assertEqual((a + (b * c)).ToPerfJson(), 'a + b * c')
> >>>> +    self.assertEqual(((a / b) * c).ToPerfJson(), 'a / b * c')
> >>>> +    self.assertEqual((a / (b * c)).ToPerfJson(), 'a / (b * c)')
> >>>> +
> >>>> +  def test_ParsePerfJson(self):
> >>>> +    # Based on an example of a real metric.
> >>>> +    before = '(a + b + c + d) / (2 * e)'
> >>>> +    after = before
> >>>> +    self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
> >>>> +
> >>>> +    # Parsing should handle events with '-' in their name. Note, in
> >>>> +    # the json file the '\' are doubled to '\\'.
> >>>> +    before = r'topdown\-fe\-bound / topdown\-slots - 1'
> >>>> +    after = before
> >>>> +    self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
> >>>> +
> >>>> +    # Parsing should handle escaped modifiers. Note, in the json file
> >>>> +    # the '\' are doubled to '\\'.
> >>>> +    before = 'arb@...nt\=0x81\,umask\=0x1@ + arb@...nt\=0x84\,umask\=0x1@'
> >>>> +    after = before
> >>>> +    self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
> >>>> +
> >>>> +    # Parsing should handle exponents in numbers.
> >>>> +    before = r'a + 1e12 + b'
> >>>> +    after = before
> >>>> +    self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
> >>>> +
> >>>> +  def test_IfElseTests(self):
> >>>> +    # if-else needs rewriting to Select and back.
> >>>> +    before = r'Event1 if #smt_on else Event2'
> >>>> +    after = f'({before})'
> >>>> +    self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
> >>>> +
> >>>> +    before = r'Event1 if 0 else Event2'
> >>>> +    after = f'({before})'
> >>>> +    self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
> >>>> +
> >>>> +    before = r'Event1 if 1 else Event2'
> >>>> +    after = f'({before})'
> >>>> +    self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
> >>>> +
> >>>> +    # Ensure the select is evaluate last.
> >>>> +    before = r'Event1 + 1 if Event2 < 2 else Event3 + 3'
> >>>> +    after = (r'Select(Event(r"Event1") + Constant(1), Event(r"Event2") < '
> >>>> +             r'Constant(2), Event(r"Event3") + Constant(3))')
> >>>> +    self.assertEqual(ParsePerfJson(before).ToPython(), after)
> >>>> +
> >>>> +    before = r'Event1 > 1 if Event2 < 2 else Event3 > 3'
> >>>> +    after = (r'Select(Event(r"Event1") > Constant(1), Event(r"Event2") < '
> >>>> +             r'Constant(2), Event(r"Event3") > Constant(3))')
> >>>> +    self.assertEqual(ParsePerfJson(before).ToPython(), after)
> >>>> +
> >>>> +    before = r'min(a + b if c > 1 else c + d, e + f)'
> >>>> +    after = r'min((a + b if c > 1 else c + d), e + f)'
> >>>> +    self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
> >>>> +
> >>>> +  def test_ToPython(self):
> >>>> +    # Based on an example of a real metric.
> >>>> +    before = '(a + b + c + d) / (2 * e)'
> >>>> +    py = ParsePerfJson(before).ToPython()
> >>>> +    after = eval(py).ToPerfJson()
> >>>> +    self.assertEqual(before, after)
> >>>> +
> >>>> +  def test_Simplify(self):
> >>>> +    before = '1 + 2 + 3'
> >>>> +    after = '6'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +    before = 'a + 0'
> >>>> +    after = 'a'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +    before = '0 + a'
> >>>> +    after = 'a'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +    before = 'a | 0'
> >>>> +    after = 'a'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +    before = '0 | a'
> >>>> +    after = 'a'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +    before = 'a * 0'
> >>>> +    after = '0'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +    before = '0 * a'
> >>>> +    after = '0'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +    before = 'a * 1'
> >>>> +    after = 'a'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +    before = '1 * a'
> >>>> +    after = 'a'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +    before = 'a if 0 else b'
> >>>> +    after = 'b'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +    before = 'a if 1 else b'
> >>>> +    after = 'a'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +    before = 'a if b else a'
> >>>> +    after = 'a'
> >>>> +    self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
> >>>> +
> >>>> +if __name__ == '__main__':
> >>>> +  unittest.main()
> >>>> --
> >>>> 2.38.0.rc1.362.ged0d419d3c-goog
> >>>>
> >>
> >> --
> >>
> >> - Arnaldo
>

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