Re: [PATCH v4 09/23] perf annotate: Deduplicate overlapping ARM SPE events for data type profiling

[Adrian Hunter]

On 08/08/2026 15:23, Tengda Wu wrote:
> When data type profiling is enabled on ARM SPE, multiple overlapping
> events (e.g., l1d-miss, tlb-access) are synthesized for a single sampled
> instruction, as shown below:
> 
>   Available samples
>   0 arm_spe_0/ts_enable=1,pa_enable=1,load_filter=1,store_filter=1,min_latency=30/
>   0 dummy:u
>   84K l1d-miss
>   95K l1d-access
>   77K llc-miss
>   58K llc-access
>   9K tlb-miss
>   108K tlb-access
>   0 branch
>   13K remote-access
>   108K memory
>   108K instructions
> 
> While 'perf report' provides an interactive menu for users to select a
> specific event to prevent duplicate counting, 'perf annotate' lacks such
> a mechanism. Consequently, it counts all instructions across these
> overlapping events, which inflates the profile and distorts the data
> type statistics.
> 
> Although using the '--itrace' option can work around this issue (e.g.:
> perf annotate --data-type --stdio --itrace=i1i), it is inconvenient for
> users to specify this explicitly every time.
> 
> To address this, introduce itrace_synth_opts.dont_overlap. Set this to true
> when data type profiling is enabled and the user has not explicitly
> specified an itrace option. Then, during arm_spe_process_auxtrace_info(),
> adjust the synthesized event options based on the dont_overlap value to
> only enable instruction event synthesis, thereby achieving automatic
> deduplication.
> 
> Signed-off-by: Tengda Wu <wutengda@xxxxxxxxxxxxxxx>
> ---
>  tools/perf/builtin-annotate.c |  8 ++++++++
>  tools/perf/util/arm-spe.c     | 17 +++++++++++++++++
>  tools/perf/util/auxtrace.h    |  2 ++
>  3 files changed, 27 insertions(+)
> 
> diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
> index 69cb72b2082a..616f54bf4868 100644
> --- a/tools/perf/builtin-annotate.c
> +++ b/tools/perf/builtin-annotate.c
> @@ -873,6 +873,14 @@ int cmd_annotate(int argc, const char **argv)
>  	annotate.session = perf_session__new(&data, &annotate.tool);
>  	if (IS_ERR(annotate.session))
>  		return PTR_ERR(annotate.session);
> +	/*
> +	 * Hardware tracing (e.g.: ARM SPE) may generate overlapping events
> +	 * per instruction. When data type profiling is enabled, enable
> +	 * dont_overlap to deduplicate them to avoid skewed stats, but only
> +	 * if user hasn't specified itrace options (respect user override).
> +	 */
> +	if (annotate.data_type && !itrace_synth_opts.set)
> +		itrace_synth_opts.dont_overlap = true;
>  
>  	annotate.session->itrace_synth_opts = &itrace_synth_opts;
>  
> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
> index 401aab529309..1721882423f6 100644
> --- a/tools/perf/util/arm-spe.c
> +++ b/tools/perf/util/arm-spe.c
> @@ -2033,6 +2033,9 @@ int arm_spe_process_auxtrace_info(union perf_event *event,
>  		/* Default nanoseconds period not supported */
>  		spe->synth_opts.period_type = PERF_ITRACE_PERIOD_INSTRUCTIONS;
>  		spe->synth_opts.period = 1;
> +
> +		if (session->itrace_synth_opts)
> +			spe->synth_opts.dont_overlap = session->itrace_synth_opts->dont_overlap;
>  	}
>  
>  	if (spe->synth_opts.period_type != PERF_ITRACE_PERIOD_INSTRUCTIONS) {
> @@ -2044,6 +2047,20 @@ int arm_spe_process_auxtrace_info(union perf_event *event,
>  		ui__warning("Arm SPE has a hardware-based sampling period.\n\n"
>  			    "--itrace periods > 1i downsample by an interval of n SPE samples rather than n instructions.\n");
>  
> +	if (spe->synth_opts.dont_overlap) {
> +		/*
> +		 * The 'instructions' event is the most comprehensive,
> +		 * synthesize it exclusively.
> +		 */
> +		spe->synth_opts.flc = false;
> +		spe->synth_opts.llc = false;
> +		spe->synth_opts.tlb = false;
> +		spe->synth_opts.branches = false;
> +		spe->synth_opts.remote_access = false;
> +		spe->synth_opts.mem = false;
> +		spe->synth_opts.instructions = true;
> +	}
> +
>  	err = arm_spe_synth_events(spe, session);
>  	if (err)
>  		goto err_free_queues;
> diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
> index 6947f3f284c0..ebb4e9e8e574 100644
> --- a/tools/perf/util/auxtrace.h
> +++ b/tools/perf/util/auxtrace.h
> @@ -80,6 +80,7 @@ enum itrace_period_type {
>   * @intr_events: whether to synthesize interrupt events
>   * @errors: whether to synthesize decoder error events
>   * @dont_decode: whether to skip decoding entirely
> + * @dont_overlap: whether to deduplicate overlapping events

This doesn't seem to match what you are actually doing, which
seems to be to choose particular default itrace options for
'perf annotate --data-type'

I wonder if this should really be handled by
itrace_synth_opts__set_default()?


>   * @log: write a decoding log
>   * @calls: limit branch samples to calls (can be combined with @returns)
>   * @returns: limit branch samples to returns (can be combined with @calls)
> @@ -128,6 +129,7 @@ struct itrace_synth_opts {
>  	bool			intr_events;
>  	bool			errors;
>  	bool			dont_decode;
> +	bool			dont_overlap;
>  	bool			log;
>  	bool			calls;
>  	bool			returns;