linux-kernel - Re: [PATCH V5 00/12] perf/core: Add ability for an event to "pause" or "resume" AUX area tracing

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Date: Wed, 24 Apr 2024 13:39:02 +0300
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>, Andi Kleen <ak@...ux.intel.com>,
 linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH V5 00/12] perf/core: Add ability for an event to "pause"
 or "resume" AUX area tracing

On 11/04/24 15:02, Adrian Hunter wrote:
> On 8/02/24 13:31, 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.  Note, thank you to James Clark (ARM) for
>> evaluating the API for Coresight.  Suzuki K Poulose (ARM) also responded
>> positively to the RFC.
>>
>> Changes to perf tools are now (since V4) fleshed out.
>>
>>
>> Changes in V5:
>>
>>     perf/core: Add aux_pause, aux_resume, aux_start_paused
>> 	Added James' Ack
>>
>>     perf/x86/intel: Do not enable large PEBS for events with aux actions or aux sampling
>> 	New patch
>>
>>     perf tools
>> 	Added Ian's Ack
>>
>> 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?
> 

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