linux-kernel - Re: [PATCH V4 10/11] perf intel-pt: Add documentation for pause / resume

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Date: Fri, 19 Jan 2024 13:28:41 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: Andi Kleen <ak@...ux.intel.com>, Peter Zijlstra <peterz@...radead.org>, 
	Ingo Molnar <mingo@...hat.com>, Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Heiko Carstens <hca@...ux.ibm.com>, 
	Thomas Richter <tmricht@...ux.ibm.com>, Hendrik Brueckner <brueckner@...ux.ibm.com>, 
	Suzuki K Poulose <suzuki.poulose@....com>, Mike Leach <mike.leach@...aro.org>, 
	James Clark <james.clark@....com>, coresight@...ts.linaro.org, 
	linux-arm-kernel@...ts.infradead.org, Yicong Yang <yangyicong@...ilicon.com>, 
	Jonathan Cameron <jonathan.cameron@...wei.com>, Will Deacon <will@...nel.org>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>, 
	linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH V4 10/11] perf intel-pt: Add documentation for pause / resume

Hello,

On Tue, Jan 16, 2024 at 4:22 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 16/01/24 13:15, Andi Kleen wrote:
> > Adrian Hunter <adrian.hunter@...el.com> writes:
> >> +
> >> +For example, to trace only the uname system call (sys_newuname) when running the
> >> +command line utility uname:
> >> +
> >> + $ perf record --kcore -e
> >> intel_pt/aux-action=start-paused/k,syscalls:sys_enter_newuname/aux-action=resume/,syscalls:sys_exit_newuname/aux-action=pause/
> >> uname
> >
> > It's unclear if the syntax works for hardware break points, kprobes, uprobes too?
>
> Yes, the perf tool syntax requires only that the group leader is
> an AUX area event like intel_pt.  Note that an attempt is made to
> automatically group AUX area events with events with aux-action,
> so grouping syntax like '{...}' is not always necessary.

Depends on the position, right?  Maybe there can be other events
without aux-action mixed with aux events.

Thanks,
Namhyung

>
> Note the current kernel implementation is called from
> __perf_event_output() which is used in nearly all cases for the
> output of samples, the exceptions being Intel BTS (which we do not
> support at the same time as Intel PT, but wouldn't make much sense
> anyway) and S390 cpumsf_output_event_pid().
>
> > That would be most useful. If it works would be good to add examples for it.
>
> OK
>