Re: [PATCH v1 04/20] perf jevents: Add tsx metric group for Intel models

Liang, Kan
2024-03-01T17:27:00Z

On 2024-03-01 11:37 a.m., Ian Rogers wrote:
> On Fri, Mar 1, 2024 at 6:52 AM Liang, Kan <kan.liang@linux.intel.com> wrote:
>>
>>
>>
>> On 2024-02-29 8:01 p.m., Ian Rogers wrote:
>>> On Thu, Feb 29, 2024 at 1:15 PM Liang, Kan <kan.liang@linux.intel.com> wrote:
>>>>
>>>>
>>>>
>>>> On 2024-02-28 7:17 p.m., Ian Rogers wrote:
>>>>> Allow duplicated metric to be dropped from json files.
>>>>>
>>>>> Signed-off-by: Ian Rogers <irogers@google.com>
>>>>> ---
>>>>> tools/perf/pmu-events/intel_metrics.py | 51 ++++++++++++++++++++++++++
>>>>> 1 file changed, 51 insertions(+)
>>>>>
>>>>> diff --git a/tools/perf/pmu-events/intel_metrics.py b/tools/perf/pmu-events/intel_metrics.py
>>>>> index 20c25d142f24..1096accea2aa 100755
>>>>> --- a/tools/perf/pmu-events/intel_metrics.py
>>>>> +++ b/tools/perf/pmu-events/intel_metrics.py
>>>>> @@ -7,6 +7,7 @@ import argparse
>>>>> import json
>>>>> import math
>>>>> import os
>>>>> +from typing import Optional
>>>>>
>>>>> parser = argparse.ArgumentParser(description="Intel perf json generator")
>>>>> parser.add_argument("-metricgroups", help="Generate metricgroups data", action='store_true')
>>>>> @@ -77,10 +78,60 @@ def Smi() -> MetricGroup:
>>>>> ])
>>>>>
>>>>>
>>>>> +def Tsx() -> Optional[MetricGroup]:
>>>>> + if args.model not in [
>>>>> + 'alderlake',
>>>>> + 'cascadelakex',
>>>>> + 'icelake',
>>>>> + 'icelakex',
>>>>> + 'rocketlake',
>>>>> + 'sapphirerapids',
>>>>> + 'skylake',
>>>>> + 'skylakex',
>>>>> + 'tigerlake',> + ]:
>>>>
>>>> Can we get ride of the model list? Otherwise, we have to keep updating
>>>> the list.
>>>
>>> Do we expect the list to update? :-)
>>
>> Yes, at least for the meteorlake and graniterapids. They should be the
>> same as alderlake and sapphirerapids. I'm not sure about the future
>> platforms.
>>
>> Maybe we can have a if args.model in list here to include all the
>> non-hybrid models which doesn't support TSX. I think the list should not
>> be changed shortly.
>>
>>> The issue is the events are in
>>> sysfs and not the json. If we added the tsx events to json then this
>>> list wouldn't be necessary, but it also would mean the events would be
>>> present in "perf list" even when TSX is disabled.
>>
>> I think there may an alternative way, to check the RTM events, e.g.,
>> RTM_RETIRED.START event. We only need to generate the metrics for the
>> platform which supports the RTM_RETIRED.START event.
>>
>>
>>>
>>>>> + return None
>>>>> +> + pmu = "cpu_core" if args.model == "alderlake" else "cpu"
>>>>
>>>> Is it possible to change the check to the existence of the "cpu" PMU
>>>> here? has_pmu("cpu") ? "cpu" : "cpu_core"
>>>
>>> The "Unit" on "cpu" events in json always just blank. On hybrid it is
>>> either "cpu_core" or "cpu_atom", so I can make this something like:
>>>
>>> pmu = "cpu_core" if metrics.HasPmu("cpu_core") else "cpu"
>>>
>>> which would be a build time test.
>>
>> Yes, I think using the "Unit" is good enough.
>>
>>>
>>>
>>>>> + cycles = Event('cycles')
>>>>> + cycles_in_tx = Event(f'{pmu}/cycles\-t/')
>>>>> + transaction_start = Event(f'{pmu}/tx\-start/')
>>>>> + cycles_in_tx_cp = Event(f'{pmu}/cycles\-ct/')
>>>>> + metrics = [
>>>>> + 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"),
>>>>> + ]
>>>>> + if args.model != 'sapphirerapids':
>>>>
>>>> Add the "tsx_cycles_per_elision" metric only if
>>>> has_event(f'{pmu}/el\-start/')?
>>>
>>> It's a sysfs event, so this wouldn't work :-(
>>
>> The below is the definition of el-start in the kernel.
>> EVENT_ATTR_STR(el-start, el_start, "event=0xc8,umask=0x1");
>>
>> The corresponding event in the event list should be HLE_RETIRED.START
>> "EventCode": "0xC8",
>> "UMask": "0x01",
>> "EventName": "HLE_RETIRED.START",
>>
>> I think we may check the HLE_RETIRED.START instead. If the
>> HLE_RETIRED.START doesn't exist, I don't see a reason why the
>> tsx_cycles_per_elision should be supported.
>>
>> Again, in the virtualization world, it's possible that the
>> HLE_RETIRED.START exists in the event list but el_start isn't available
>> in the sysfs. I think it has to be specially handle in the test as well.
>
> So we keep the has_event test on the sysfs event to handle the
> virtualization and disabled case. We use HLE_RETIRED.START to detect
> whether the model supports TSX.

Yes. I think the JSON event always keeps the latest status of an event.
If an event is deprecated someday, I don't think there is a reason to
keep any metrics including the event. So we should use it to check
whether to generate a metrics.

The sysfs event tells if the current kernel support the event. It should
be used to check whether a metrics should be used/enabled.

> Should the event be the sysfs or json
> version? i.e.
>
> "MetricExpr": "(cycles\\-t / el\\-start if
> has_event(el\\-start) else 0)",
>
> or
>
> "MetricExpr": "(cycles\\-t / HLE_RETIRED.START if
> has_event(el\\-start) else 0)",
>
> I think I favor the former for some consistency with the has_event.
>

Agree, the former looks good to me too.

> Using HLE_RETIRED.START means the set of TSX models goes from:
> 'alderlake',
> 'cascadelakex',
> 'icelake',
> 'icelakex',
> 'rocketlake',
> 'sapphirerapids',
> 'skylake',
> 'skylakex',
> 'tigerlake',
>
> To:
> broadwell
> broadwellde
> broadwellx
> cascadelakex
> haswell
> haswellx
> icelake
> rocketlake
> skylake
> skylakex
>
> Using RTM_RETIRED.START it goes to:
> broadwell
> broadwellde
> broadwellx
> cascadelakex
> emeraldrapids
> graniterapids
> haswell
> haswellx
> icelake
> icelakex
> rocketlake
> sapphirerapids
> skylake
> skylakex
> tigerlake
>
> So I'm not sure it is working equivalently to what we have today,
> which may be good or bad. Here is what I think the code should look
> like:

Yes, there should be some changes. But I think the changes should be good.

For icelakex, the HLE_RETIRED.START has been deprecated. I don't see a
reason why should perf keep the tsx_cycles_per_elision metric.

For alderlake, TSX is deprecated. The perf should drop the related
metrics as well.
https://edc.intel.com/content/www/us/en/design/ipla/software-development-platforms/client/platforms/alder-lake-desktop/12th-generation-intel-core-processors-datasheet-volume-1-of-2/001/deprecated-technologies/

>
> def Tsx() -> Optional[MetricGroup]:
> pmu = "cpu_core" if CheckPmu("cpu_core") else "cpu"
> cycles = Event('cycles')
> 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/')
> 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")
>
> Wdyt?

Looks good to me.

Thanks,
Kan
>
> Thanks,
> Ian
>
>> Thanks,
>> Kan
>>
>>>
>>> Thanks,
>>> Ian
>>>
>>>> Thanks,
>>>> Kan
>>>>
>>>>> + elision_start = Event(f'{pmu}/el\-start/')
>>>>> + metrics += [
>>>>> + 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"),
>>>>> + ]
>>>>> + return MetricGroup('transaction', metrics)
>>>>> +
>>>>> +
>>>>> all_metrics = MetricGroup("", [
>>>>> Idle(),
>>>>> Rapl(),
>>>>> Smi(),
>>>>> + Tsx(),
>>>>> ])
>>>>>
>>>>> if args.metricgroups:
>>>