Date:   Tue, 7 Dec 2021 18:04:18 +0100
From:   Jiri Olsa <jolsa@redhat.com>
To:     "nakamura.shun@fujitsu.com" <nakamura.shun@fujitsu.com>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Rob Herring <robh@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-perf-users@vger.kernel.org" <linux-perf-users@vger.kernel.org>
Subject: Re: libperf: lack of interface
Message-ID: <Ya+UEn+qjUEzgKfq@krava>
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On Tue, Dec 07, 2021 at 05:49:16AM +0000, nakamura.shun@fujitsu.com wrote:
> Hi jirka
> 
> > > > On Mon, Oct 18, 2021 at 08:57:20AM +0000, nakamura.shun@fujitsu.com wrote:
> > > > > Hi
> > > > > 
> > > > > >?> On Wed, Sep 01, 2021 at 10:36:40AM -0300, Arnaldo Carvalho de Melo wrote:
> > > > > >?> > Em Wed, Sep 01, 2021 at 09:45:10AM +0000, nakamura.shun@fujitsu.com escreveu:
> > > > > >?> > > Hello.
> > > > > >?> > >
> > > > > >?> > > I'm trying to change rdpmc test in perf_event_tests[1] to use libperf, but libperf doesn't have enough interfaces.
> > > > > >?> > > Does anyone plan to implement any of these libperf features?
> > > > > >?> > >
> > > > > >?> > > - Interfaces that can run ioctl (PERF_EVENT_IOC_RESET) from userland
> > > > > >?> > > - Interfaces that can run fcntl (SIGIO) from userland
> > > > > >?>
> > > > > >?> hi,
> > > > > >?> we could add perf_evsel__fd like below, would it help your usecase?
> > > > > >?>
> > > > > >?> if you described your usecases in more details we could
> > > > > >?> see if we could add/move something to libperf for that
> > > > > >?>
> > > > > >?> as Arnaldo said below it could be already in tools/perf/util/*.c
> > > > > >?> somewhere ;-)
> > > > > >?
> > > > > >?As Peter says, I understood that for rdpmc, no reset is needed.
> > > > > >?
> > > > > >?However, PAPI resets it explicitly, for example, at PAPI_reset.
> > > > > >?In other, PAPI also has the ability to call PERF_EVENT_IOC_REFLESH on overflow to call a user-registered handler, using SIGIO.
> > > > > >?
> > > > > >?I think it is desirable to be able to achieve similar functionality.
> > > > > 
> > > > > Does anyone have any comments?
> > > > 
> > > > I'll try to add that functionality soon,
> > > > I'll cc you on patch
> > > 
> > > Thank you.
> > > I look forward to your patch.
> > 
> > Do you have a specific plan? 
> > I would like to know the rough period until your patch is made.
>  
> I will also try to implement these interfaces.

sorry for late reply, please do

thanks,
jirka