From: Randy Dunlap <rdunlap@infradead.org>
To: Ian Rogers <irogers@google.com>
Cc: Kan Liang <kan.liang@linux.intel.com>,
Thomas Richter <tmricht@linux.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Bjorn Helgaas <bhelgaas@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Jing Zhang <renyu.zj@linux.alibaba.com>,
James Clark <james.clark@arm.com>,
Ravi Bangoria <ravi.bangoria@amd.com>,
linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v5 2/6] perf Document: Sysfs event names must be lower or upper case
Date: Mon, 13 May 2024 11:54:29 -0700 [thread overview]
Message-ID: <f24eef54-e32f-41bc-b4cd-13ca83e1ea48@infradead.org> (raw)
In-Reply-To: <CAP-5=fWHrX5AgH8=62f3=a-SSqUACXX1rkDZJ-WV1RcNieeHFA@mail.gmail.com>
On 5/13/24 9:22 AM, Ian Rogers wrote:
> On Sun, May 12, 2024 at 3:08 PM Randy Dunlap <rdunlap@infradead.org> wrote:
>>
>> Hi,
>>
>> On 5/2/24 2:35 PM, Ian Rogers wrote:
>>> To avoid directory scans in perf it is going to be assumed that sysfs
>>> event names are either lower or upper case.
>>>
>>> Signed-off-by: Ian Rogers <irogers@google.com>
>>> Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
>>> ---
>>> .../ABI/testing/sysfs-bus-event_source-devices-events | 6 ++++++
>>> 1 file changed, 6 insertions(+)
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-bus-event_source-devices-events b/Documentation/ABI/testing/sysfs-bus-event_source-devices-events
>>> index 77de58d03822..e7efeab2ee83 100644
>>> --- a/Documentation/ABI/testing/sysfs-bus-event_source-devices-events
>>> +++ b/Documentation/ABI/testing/sysfs-bus-event_source-devices-events
>>> @@ -37,6 +37,12 @@ Description: Per-pmu performance monitoring events specific to the running syste
>>> performance monitoring event supported by the <pmu>. The name
>>> of the file is the name of the event.
>>>
>>> + As performance monitoring event names are case
>>> + insensitive in the perf tool, the perf tool only looks
>>> + for lower or upper case event names in sysfs to avoid
>>> + scanning the directory. It is therefore required the
>>> + name of the event here is either lower or upper case.
>>> +
>>
>> This is ambiguous to me. Is it clear to everyone else?
>>
>> "for lower or upper case event names":
>>
>> Is that a logical OR or an exclusive OR?
>> "AbC" contains lower case or upper case characters. :)
>>
>> I think the code [static bool permitted_event_name()]
>> implements an exclusive OR.
>> The code also allows event names to contain numbers AFAICT.
>> The documentation doesn't mention this.
>>
>> HTH.
>>
>>> File contents:
>>>
>>> <term>[=<value>][,<term>[=<value>]]...
>
> Sorry, this reads like a troll. Assuming good intentions, could you
> propose a fix in the form of a patch? When a word is made upper or
Sure, I'll send a patch.
No trolling here.
> lower case I believe it is generally assumed the operation applies to
> all characters within the word, but I'm happy to see ambiguity cleared
> up.
>
> Thanks,
> Ian
--
#Randy
https://people.kernel.org/tglx/notes-about-netiquette
https://subspace.kernel.org/etiquette.html
next prev parent reply other threads:[~2024-05-13 18:54 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-02 21:35 [PATCH v5 0/6] Assume sysfs event names are always the same case Ian Rogers
2024-05-02 21:35 ` [PATCH v5 1/6] perf test pmu-events: Make it clearer that pmu-events tests json events Ian Rogers
2024-05-02 21:35 ` [PATCH v5 2/6] perf Document: Sysfs event names must be lower or upper case Ian Rogers
2024-05-12 22:08 ` Randy Dunlap
2024-05-13 16:22 ` Ian Rogers
2024-05-13 18:54 ` Randy Dunlap [this message]
2024-05-02 21:35 ` [PATCH v5 3/6] perf test pmu: Refactor format test and exposed test APIs Ian Rogers
2024-05-02 21:35 ` [PATCH v5 4/6] perf test pmu: Add an eagerly loaded event test Ian Rogers
2024-05-02 21:35 ` [PATCH v5 5/6] perf test pmu: Test all sysfs PMU event names are the same case Ian Rogers
2024-05-02 21:35 ` [PATCH v5 6/6] perf pmu: Assume sysfs events are always " Ian Rogers
2024-05-03 20:09 ` [PATCH v5 0/6] Assume sysfs event names " Arnaldo Carvalho de Melo
2024-05-06 15:34 ` Thomas Richter
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