linux-kernel - Re: [PATCH v1 1/2] perf auxtrace: Add 'T' itrace option for timestamp trace

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Message-ID: <ZUlgM8pgf19UeyM9@kernel.org>
Date:   Mon, 6 Nov 2023 18:52:51 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Leo Yan <leo.yan@...aro.org>, James Clark <james.clark@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        John Garry <john.g.garry@...cle.com>,
        Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>, coresight@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] perf auxtrace: Add 'T' itrace option for
 timestamp trace

Em Thu, Oct 19, 2023 at 01:47:15PM +0300, Adrian Hunter escreveu:
> On 14/10/23 10:45, Leo Yan wrote:
> > An AUX trace can contain timestamp, but in some situations, the hardware
> > trace module (e.g. Arm CoreSight) cannot decide the traced timestamp is
> > the same source with CPU's time, thus the decoder can not use the
> > timestamp trace for samples.
> > 
> > This patch introduces 'T' itrace option. If users know the platforms
> 
> "If users know" <- how would users know?  Could the kernel
> or tools also figure it out?

Adrian, I'm trying to go all the outstanding patches, do you still have
any issues with this series?

- Arnaldo
 
> > they are working on have the same time counter with CPUs, users can
> > use this new option to tell a decoder for using timestamp trace as
> > kernel time.
> > 
> > Signed-off-by: Leo Yan <leo.yan@...aro.org>
> > ---
> >  tools/perf/Documentation/itrace.txt | 1 +
> >  tools/perf/util/auxtrace.c          | 3 +++
> >  tools/perf/util/auxtrace.h          | 3 +++
> >  3 files changed, 7 insertions(+)
> > 
> > diff --git a/tools/perf/Documentation/itrace.txt b/tools/perf/Documentation/itrace.txt
> > index a97f95825b14..19cc179be9a7 100644
> > --- a/tools/perf/Documentation/itrace.txt
> > +++ b/tools/perf/Documentation/itrace.txt
> > @@ -25,6 +25,7 @@
> >  		q	quicker (less detailed) decoding
> >  		A	approximate IPC
> >  		Z	prefer to ignore timestamps (so-called "timeless" decoding)
> > +		T	use the timestamp trace as kernel time
> >  
> >  	The default is all events i.e. the same as --itrace=iybxwpe,
> >  	except for perf script where it is --itrace=ce
> > diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
> > index a0368202a746..f528c4364d23 100644
> > --- a/tools/perf/util/auxtrace.c
> > +++ b/tools/perf/util/auxtrace.c
> > @@ -1638,6 +1638,9 @@ int itrace_do_parse_synth_opts(struct itrace_synth_opts *synth_opts,
> >  		case 'Z':
> >  			synth_opts->timeless_decoding = true;
> >  			break;
> > +		case 'T':
> > +			synth_opts->use_timestamp = true;
> > +			break;
> >  		case ' ':
> >  		case ',':
> >  			break;
> > diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
> > index 29eb82dff574..55702215a82d 100644
> > --- a/tools/perf/util/auxtrace.h
> > +++ b/tools/perf/util/auxtrace.h
> > @@ -99,6 +99,7 @@ enum itrace_period_type {
> >   * @remote_access: whether to synthesize remote access events
> >   * @mem: whether to synthesize memory events
> >   * @timeless_decoding: prefer "timeless" decoding i.e. ignore timestamps
> > + * @use_timestamp: use the timestamp trace as kernel time
> >   * @vm_time_correlation: perform VM Time Correlation
> >   * @vm_tm_corr_dry_run: VM Time Correlation dry-run
> >   * @vm_tm_corr_args:  VM Time Correlation implementation-specific arguments
> > @@ -146,6 +147,7 @@ struct itrace_synth_opts {
> >  	bool			remote_access;
> >  	bool			mem;
> >  	bool			timeless_decoding;
> > +	bool			use_timestamp;
> >  	bool			vm_time_correlation;
> >  	bool			vm_tm_corr_dry_run;
> >  	char			*vm_tm_corr_args;
> > @@ -678,6 +680,7 @@ bool auxtrace__evsel_is_auxtrace(struct perf_session *session,
> >  "				q:			quicker (less detailed) decoding\n" \
> >  "				A:			approximate IPC\n" \
> >  "				Z:			prefer to ignore timestamps (so-called \"timeless\" decoding)\n" \
> > +"				T:			use the timestamp trace as kernel time\n" \
> >  "				PERIOD[ns|us|ms|i|t]:   specify period to sample stream\n" \
> >  "				concatenate multiple options. Default is iybxwpe or cewp\n"
> >  
> 

-- 

- Arnaldo