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 <[email protected]>
Reviewed-by: Kan Liang <[email protected]>
---
.../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.
+
File contents:
<term>[=<value>][,<term>[=<value>]]...
--
2.45.0.rc1.225.g2a3ae87e7f-goog
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 <[email protected]>
> Reviewed-by: Kan Liang <[email protected]>
> ---
> .../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>]]...
--
#Randy
https://people.kernel.org/tglx/notes-about-netiquette
https://subspace.kernel.org/etiquette.html
On Sun, May 12, 2024 at 3:08 PM Randy Dunlap <[email protected]> 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 <[email protected]>
> > Reviewed-by: Kan Liang <[email protected]>
> > ---
> > .../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
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
On 5/13/24 9:22 AM, Ian Rogers wrote:
> On Sun, May 12, 2024 at 3:08 PM Randy Dunlap <[email protected]> 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 <[email protected]>
>>> Reviewed-by: Kan Liang <[email protected]>
>>> ---
>>> .../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