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Message-ID: <8a2ea58f-f835-4d1a-8bd6-3a63b3b0db94@intel.com>
Date: Thu, 19 Oct 2023 13:47:15 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Leo Yan <leo.yan@...aro.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
James Clark <james.clark@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Mike Leach <mike.leach@...aro.org>
Cc: 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
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?
> 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"
>
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