linux-kernel - Re: [PATCH RFC V2 0/4] perf/core: Add ability for an event to "pause" or "resume" AUX area tracing

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Date: Tue, 19 Dec 2023 08:05:34 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Peter Zijlstra <peterz@...radead.org>, James Clark <james.clark@....com>
Cc: 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>, 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>, Namhyung Kim <namhyung@...nel.org>,
 Ian Rogers <irogers@...gle.com>, linux-kernel@...r.kernel.org,
 linux-perf-users@...r.kernel.org
Subject: Re: [PATCH RFC V2 0/4] perf/core: Add ability for an event to "pause"
 or "resume" AUX area tracing

On 8/12/23 19:24, Adrian Hunter wrote:
> Hi
> 
> Hardware traces, such as instruction traces, can produce a vast amount of
> trace data, so being able to reduce tracing to more specific circumstances
> can be useful.
> 
> The ability to pause or resume tracing when another event happens, can do
> that.
> 
> These patches add such a facilty and show how it would work for Intel
> Processor Trace.
> 
> Maintainers of other AUX area tracing implementations are requested to
> consider if this is something they might employ and then whether or not
> the ABI would work for them.
> 
> Changes to perf tools are not fleshed out yet.
> 
> 
> Changes in RFC V2:
> 
>       Use ->stop() / ->start() instead of ->pause_resume()
>       Move aux_start_paused bit into aux_output_cfg
>       Tighten up when Intel PT pause / resume is allowed
>       Add an example of how it might work for CoreSight

Any comments?

> 
> 
> Adrian Hunter (4):
>       perf/core: Add aux_pause, aux_resume, aux_start_paused
>       perf/x86/intel/pt: Add support for pause / resume
>       perf tools: Add support for AUX area pause / resume
>       coresight: Have a stab at support for pause / resume
> 
>  arch/x86/events/intel/pt.c                       | 63 ++++++++++++++++++++-
>  arch/x86/events/intel/pt.h                       |  4 ++
>  drivers/hwtracing/coresight/coresight-etm-perf.c | 29 ++++++++--
>  include/linux/perf_event.h                       | 15 +++++
>  include/uapi/linux/perf_event.h                  | 11 +++-
>  kernel/events/core.c                             | 72 +++++++++++++++++++++++-
>  kernel/events/internal.h                         |  1 +
>  tools/include/uapi/linux/perf_event.h            | 11 +++-
>  tools/perf/util/auxtrace.c                       |  4 ++
>  tools/perf/util/evsel.c                          |  9 +++
>  tools/perf/util/evsel_config.h                   |  6 ++
>  tools/perf/util/parse-events.c                   | 33 +++++++++++
>  tools/perf/util/parse-events.h                   |  3 +
>  tools/perf/util/parse-events.l                   |  3 +
>  tools/perf/util/perf_event_attr_fprintf.c        |  3 +
>  15 files changed, 255 insertions(+), 12 deletions(-)
> 
> 
> Regards
> Adrian