On 14/10/2023 08:45, 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 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@linaro.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
Maybe "Treat hardware timestamps as kernel time (trace and CPU time use same clock source)" would be clearer.
And another point, although this isn't really related to this patch, but why do we have the single letter arguments for itrace? It seems like it massively restricts the available options and makes the command lines hard to read because they don't have long forms. Why not just have them as normal arguments?
If it's a backwards compatibility thing, would there be any objection to adding this new option as a normal one rather than an itrace one?
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;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;
And then this one could be like "hw_time_is_kernel_time", but I'm stuggling to think of something shorter. Maybe your one is fine along with the comment.