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

[Adrian Hunter]

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?