On 27/08/2023 14:35, Leo Yan wrote:
> When users pass the option '--timestamp' or '-T' in the record command,
> all events will set the PERF_SAMPLE_TIME bit in the attribution. In
> this case, the AUX event will record the kernel timestamp, but it
> doesn't mean Arm CoreSight enables timestamp packets in its hardware
> tracing.
>
> If the option '--timestamp' or '-T' is set, this patch always enables
> Arm CoreSight timestamp, as a result, the bit 28 in event's config is to
> be set.
>
> Before:
>
> # perf record -e cs_etm// --per-thread --timestamp -- ls
> # perf script --header-only
> ...
> # event : name = cs_etm//, , id = { 69 }, type = 12, size = 136,
> config = 0, { sample_period, sample_freq } = 1,
> sample_type = IP|TID|TIME|CPU|IDENTIFIER, read_format = ID|LOST,
> disabled = 1, enable_on_exec = 1, sample_id_all = 1, exclude_guest = 1
> ...
>
> After:
>
> # perf record -e cs_etm// --per-thread --timestamp -- ls
> # perf script --header-only
> ...
> # event : name = cs_etm//, , id = { 49 }, type = 12, size = 136,
> config = 0x10000000, { sample_period, sample_freq } = 1,
> sample_type = IP|TID|TIME|CPU|IDENTIFIER, read_format = ID|LOST,
> disabled = 1, enable_on_exec = 1, sample_id_all = 1, exclude_guest = 1
> ...
>
> Signed-off-by: Leo Yan <[email protected]>
Reviewed-by: James Clark <[email protected]>
> ---
> tools/perf/arch/arm/util/cs-etm.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
> index cf9ef9ba800b..58c506e9788d 100644
> --- a/tools/perf/arch/arm/util/cs-etm.c
> +++ b/tools/perf/arch/arm/util/cs-etm.c
> @@ -442,6 +442,15 @@ static int cs_etm_recording_options(struct auxtrace_record *itr,
> "contextid", 1);
> }
>
> + /*
> + * When the option '--timestamp' or '-T' is enabled, the PERF_SAMPLE_TIME
> + * bit is set for all events. In this case, always enable Arm CoreSight
> + * timestamp tracing.
> + */
> + if (opts->sample_time_set)
> + evsel__set_config_if_unset(cs_etm_pmu, cs_etm_evsel,
> + "timestamp", 1);
> +
> /* Add dummy event to keep tracking */
> err = parse_event(evlist, "dummy:u");
> if (err)