linux-kernel - Re: [PATCH v4 06/22] perf jevents: Add tsx metric group for Intel models

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Message-ID: <244b4c80-2ab2-4248-b930-22fea9ed6429@linux.intel.com>
Date: Wed, 6 Nov 2024 12:52:56 -0500
From: "Liang, Kan" <kan.liang@...ux.intel.com>
To: Ian Rogers <irogers@...gle.com>, Peter Zijlstra <peterz@...radead.org>,
 Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Jiri Olsa <jolsa@...nel.org>, Adrian Hunter <adrian.hunter@...el.com>,
 linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
 Perry Taylor <perry.taylor@...el.com>, Samantha Alt
 <samantha.alt@...el.com>, Caleb Biggers <caleb.biggers@...el.com>,
 Weilin Wang <weilin.wang@...el.com>, Edward Baker <edward.baker@...el.com>
Subject: Re: [PATCH v4 06/22] perf jevents: Add tsx metric group for Intel
 models



On 2024-09-26 1:50 p.m., Ian Rogers wrote:
> Allow duplicated metric to be dropped from json files. Detect when TSX
> is supported by a model by using the json events, use sysfs events at
> runtime as hypervisors, etc. may disable TSX.
> 
> Add CheckPmu to metric to determine if which PMUs have been associated
> with the loaded events.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/pmu-events/intel_metrics.py | 52 +++++++++++++++++++++++++-
>  1 file changed, 51 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/pmu-events/intel_metrics.py b/tools/perf/pmu-events/intel_metrics.py
> index f34b4230a4ee..58e243695f0a 100755
> --- a/tools/perf/pmu-events/intel_metrics.py
> +++ b/tools/perf/pmu-events/intel_metrics.py
> @@ -1,12 +1,13 @@
>  #!/usr/bin/env python3
>  # SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
> -from metric import (d_ratio, has_event, max, Event, JsonEncodeMetric,
> +from metric import (d_ratio, has_event, max, CheckPmu, Event, JsonEncodeMetric,
>                      JsonEncodeMetricGroupDescriptions, LoadEvents, Metric,
>                      MetricGroup, MetricRef, Select)
>  import argparse
>  import json
>  import math
>  import os
> +from typing import Optional
>  
>  # Global command line arguments.
>  _args = None
> @@ -74,6 +75,54 @@ def Smi() -> MetricGroup:
>      ], description = 'System Management Interrupt metrics')
>  
>  
> +def Tsx() -> Optional[MetricGroup]:
> +  pmu = "cpu_core" if CheckPmu("cpu_core") else "cpu"
> +  cycles = Event('cycles')

Isn't the pmu prefix required for cycles as well?

> +  cycles_in_tx = Event(f'{pmu}/cycles\-t/')
> +  cycles_in_tx_cp = Event(f'{pmu}/cycles\-ct/')
> +  try:
> +    # Test if the tsx event is present in the json, prefer the
> +    # sysfs version so that we can detect its presence at runtime.
> +    transaction_start = Event("RTM_RETIRED.START")
> +    transaction_start = Event(f'{pmu}/tx\-start/')

What's the difference between this check and the later has_event() check?

All the tsx related events are model-specific events. We should check
them all before using it.

Thanks,
Kan
> +  except:> +    return None
> +
> +  elision_start = None
> +  try:
> +    # Elision start isn't supported by all models, but we'll not
> +    # generate the tsx_cycles_per_elision metric in that
> +    # case. Again, prefer the sysfs encoding of the event.
> +    elision_start = Event("HLE_RETIRED.START")
> +    elision_start = Event(f'{pmu}/el\-start/')
> +  except:
> +    pass
> +
> +  return MetricGroup('transaction', [
> +      Metric('tsx_transactional_cycles',
> +             'Percentage of cycles within a transaction region.',
> +             Select(cycles_in_tx / cycles, has_event(cycles_in_tx), 0),
> +             '100%'),
> +      Metric('tsx_aborted_cycles', 'Percentage of cycles in aborted transactions.',
> +             Select(max(cycles_in_tx - cycles_in_tx_cp, 0) / cycles,
> +                    has_event(cycles_in_tx),
> +                    0),
> +             '100%'),
> +      Metric('tsx_cycles_per_transaction',
> +             'Number of cycles within a transaction divided by the number of transactions.',
> +             Select(cycles_in_tx / transaction_start,
> +                    has_event(cycles_in_tx),
> +                    0),
> +             "cycles / transaction"),
> +      Metric('tsx_cycles_per_elision',
> +             'Number of cycles within a transaction divided by the number of elisions.',
> +             Select(cycles_in_tx / elision_start,
> +                    has_event(elision_start),
> +                    0),
> +             "cycles / elision") if elision_start else None,
> +  ], description="Breakdown of transactional memory statistics")
> +
> +
>  def main() -> None:
>    global _args
>  
> @@ -100,6 +149,7 @@ def main() -> None:
>        Idle(),
>        Rapl(),
>        Smi(),
> +      Tsx(),
>    ])
>  
>