Messages in this thread | | | From | Ian Rogers <> | Date | Wed, 31 Jan 2024 08:53:06 -0800 | Subject | Re: [PATCH V4 00/11] perf/core: Add ability for an event to "pause" or "resume" AUX area tracing |
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On Mon, Jan 29, 2024 at 4:49 AM Adrian Hunter <adrian.hunter@intel.com> wrote: > > 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?
I think the tools side looks good. The parsing changes match the existing style. I wonder if it wouldn't be better to handle the valid strings (pause, resume, etc.) in the lexer rather than a separate parse function, but the pattern used matches the existing one. You can have my Acked-by on the tools changes, although the subtleties of ARM PMUs makes me somewhat nervous in this regard.
Thanks, Ian
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