Re: [PATCH v2] perf evsel: Don't set sample_regs_intr/sample_regs_user for dummy event
From: Arnaldo Carvalho de Melo
Date: Tue Aug 04 2020 - 08:32:15 EST
Em Tue, Aug 04, 2020 at 10:06:56AM +0300, Adrian Hunter escreveu:
> On 29/07/20 10:23 am, Jin, Yao wrote:
> > Hi Adrian,
> > Could you help to check if following condition will break PT?
> > "(opts->sample_intr_regs && !evsel->no_aux_samples &&
> > !evsel__is_dummy_event(evsel))"
> Sorry for slow response - I've been away.
> This is fine. It will not break PT.
> no_aux_samples is useful for evsels that have been added by the code rather
> than requested by the user. For old kernels PT adds sched_switch tracepoint
> to track context switches (before the current context switch event was
> added) and having auxiliary sample information unnecessarily uses up space
> in the perf buffer.
> Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Thanks for checking and providing the comment, that I added as a
committer note together with your Acked-by, appreciated.