linux-kernel - Re: [PATCH V4 00/11] perf/core: Add ability for an event to "pause" or "resume" AUX area tracing

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Date: Mon, 29 Jan 2024 14:48:42 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Peter Zijlstra <peterz@...radead.org>
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>, 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>, Namhyung Kim <namhyung@...nel.org>,
 Ian Rogers <irogers@...gle.com>, linux-kernel@...r.kernel.org,
 linux-perf-users@...r.kernel.org
Subject: Re: [PATCH V4 00/11] perf/core: Add ability for an event to "pause"
 or "resume" AUX area tracing

On 11/01/24 10:19, 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 now (since V4) fleshed out.
> 
> 
> Changes in V4:
> 
>     perf/core: Add aux_pause, aux_resume, aux_start_paused
> 	Rename aux_output_cfg -> aux_action
> 	Reorder aux_action bits from:
> 		aux_pause, aux_resume, aux_start_paused
> 	to:
> 		aux_start_paused, aux_pause, aux_resume
> 	Fix aux_action bits __u64 -> __u32
> 
>     coresight: Have a stab at support for pause / resume
> 	Dropped
> 
>     perf tools
> 	All new patches
> 
> Changes in RFC V3:
> 
>     coresight: Have a stab at support for pause / resume
> 	'mode' -> 'flags' so it at least compiles
> 
> 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 more comments?