2021-06-14 07:21:59

by [email protected]

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Subject: libperf : Can not create event group

Hello.

perf_evsel__open cannot create an event group because it set group_fd
to -1 when it ran perf_event_open.
Is there any reason why group_fd is fixed at -1?

Best Regards
Shunsuke


2021-06-14 11:35:20

by Jiri Olsa

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Subject: Re: libperf : Can not create event group

On Mon, Jun 14, 2021 at 07:17:53AM +0000, [email protected] wrote:
> Hello.
>
> perf_evsel__open cannot create an event group because it set group_fd
> to -1 when it ran perf_event_open.
> Is there any reason why group_fd is fixed at -1?

hi,
there'no leader link on this level yet (in struct evsel)
so this is not implemented at the moment

jirka

>
> Best Regards
> Shunsuke

2021-06-22 08:06:51

by [email protected]

[permalink] [raw]
Subject: Re: libperf : Can not create event group

Hi, jirka

> there'no leader link on this level yet (in struct evsel)
> so this is not implemented at the moment

Thanks for the info.

Do you have any plans to support the event group in libperf?

Best Regards
Shunsuke

2021-06-22 21:08:11

by Jiri Olsa

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Subject: Re: libperf : Can not create event group

On Tue, Jun 22, 2021 at 07:57:56AM +0000, [email protected] wrote:
> Hi, jirka
>
> > there'no leader link on this level yet (in struct evsel)
> > so this is not implemented at the moment
>
> Thanks for the info.
>
> Do you have any plans to support the event group in libperf?

hi,
not until now I guess ;-) what's your use case?

jirka

2021-06-28 08:53:47

by [email protected]

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Subject: Re: libperf : Can not create event group

Hi, jirka

> > Do you have any plans to support the event group in libperf?
>
> hi,
> not until now I guess ;-) what's your use case?

PAPI uses event group to measure multiple events.
libperf uses multiplexing regardless of the user's intent.

I thought it would be nice if users could choose to use multiplexing or event groups.


Best Regards
Shunsuke

jirka