Re: [PATCH v5 10/26] perf annotate: Default to --itrace=i1i for data type profiling
From: Adrian Hunter <adrian.hunter@intel.com>
Date: 2026-09-09 15:38:37
Also in:
lkml, llvm
On 08/09/2026 16:05, Tengda Wu wrote:
ARM SPE-based sampling can synthesize multiple events on a single instruction, as shown below. This would affect data type profiling statistics: 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.default_single_event_per_ip. Set this field to true when data type profiling is enabled and the user has not explicitly specified an itrace option. In itrace_synth_opts__set_default(), use this flag to default to synthesizing at most one event per IP (equivalent to --itrace=i1i) to prevent duplicate sample counts. Signed-off-by: Tengda Wu <redacted>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
quoted hunk ↗ jump to hunk
--- tools/perf/builtin-annotate.c | 8 ++++++++ tools/perf/util/arm-spe.c | 5 ++++- tools/perf/util/auxtrace.c | 12 ++++++++++-- tools/perf/util/auxtrace.h | 7 ++++++- tools/perf/util/cs-etm.c | 2 +- tools/perf/util/intel-bts.c | 2 +- tools/perf/util/intel-pt.c | 3 ++- 7 files changed, 32 insertions(+), 7 deletions(-)diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c index 69cb72b2082a..d5b66893c47c 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 synthesize multiple events per + * instruction. When data type profiling is enabled, default to synthesizing + * at most one event (equivalent to --itrace=i1i) to prevent skewed + * statistics. + */ + if (annotate.data_type && !itrace_synth_opts.set) + itrace_synth_opts.default_single_event_per_ip = 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..ae7a5e9c3892 100644 --- a/tools/perf/util/arm-spe.c +++ b/tools/perf/util/arm-spe.c@@ -2029,7 +2029,10 @@ int arm_spe_process_auxtrace_info(union perf_event *event, if (session->itrace_synth_opts && session->itrace_synth_opts->set) { spe->synth_opts = *session->itrace_synth_opts; } else { - itrace_synth_opts__set_default(&spe->synth_opts, false); + struct itrace_synth_opts *opts = session->itrace_synth_opts; + bool single_event_per_ip = opts ? opts->default_single_event_per_ip : false; + + itrace_synth_opts__set_default(&spe->synth_opts, false, single_event_per_ip); /* Default nanoseconds period not supported */ spe->synth_opts.period_type = PERF_ITRACE_PERIOD_INSTRUCTIONS; spe->synth_opts.period = 1;diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c index aa749e1c3036..ed2113190785 100644 --- a/tools/perf/util/auxtrace.c +++ b/tools/perf/util/auxtrace.c@@ -1478,8 +1478,15 @@ s64 perf_event__process_auxtrace(const struct perf_tool *tool __maybe_unused, #define PERF_ITRACE_MAX_LAST_BRANCH_SZ 1024 void itrace_synth_opts__set_default(struct itrace_synth_opts *synth_opts, - bool no_sample) + bool no_sample, bool single_event_per_ip) { + if (single_event_per_ip) { + synth_opts->instructions = true; + synth_opts->period_type = PERF_ITRACE_PERIOD_INSTRUCTIONS; + synth_opts->period = 1; + return; + } + synth_opts->branches = true; synth_opts->transactions = true; synth_opts->ptwrites = true;@@ -1582,7 +1589,8 @@ int itrace_do_parse_synth_opts(struct itrace_synth_opts *synth_opts, if (!str) { itrace_synth_opts__set_default(synth_opts, - synth_opts->default_no_sample); + synth_opts->default_no_sample, + synth_opts->default_single_event_per_ip); return 0; }diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h index 6947f3f284c0..5012bead1b92 100644 --- a/tools/perf/util/auxtrace.h +++ b/tools/perf/util/auxtrace.h@@ -65,6 +65,10 @@ enum itrace_period_type { * struct itrace_synth_opts - AUX area tracing synthesis options. * @set: indicates whether or not options have been set * @default_no_sample: Default to no sampling. + * @default_single_event_per_ip: Default to synthesizing at most 1 event per IP + * (equivalent to --itrace=i1i). Used by commands + * like 'perf annotate --data-type' to avoid duplicate + * sample counts for a single instruction. * @inject: indicates the event (not just the sample) must be fully synthesized * because 'perf inject' will write it out * @instructions: whether to synthesize 'instructions' events@@ -117,6 +121,7 @@ enum itrace_period_type { struct itrace_synth_opts { bool set; bool default_no_sample; + bool default_single_event_per_ip; bool inject; bool instructions; bool cycles;@@ -622,7 +627,7 @@ int itrace_do_parse_synth_opts(struct itrace_synth_opts *synth_opts, int itrace_parse_synth_opts(const struct option *opt, const char *str, int unset); void itrace_synth_opts__set_default(struct itrace_synth_opts *synth_opts, - bool no_sample); + bool no_sample, bool single_event_per_ip); size_t perf_event__fprintf_auxtrace_error(union perf_event *event, FILE *fp); void perf_session__auxtrace_error_inc(struct perf_session *session,diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c index 114b3cd2da49..2d1ab34f7b6b 100644 --- a/tools/perf/util/cs-etm.c +++ b/tools/perf/util/cs-etm.c@@ -3626,7 +3626,7 @@ int cs_etm__process_auxtrace_info_full(union perf_event *event, etm->synth_opts = *session->itrace_synth_opts; } else { itrace_synth_opts__set_default(&etm->synth_opts, - session->itrace_synth_opts->default_no_sample); + session->itrace_synth_opts->default_no_sample, false); etm->synth_opts.callchain = false; etm->synth_opts.thread_stack = session->itrace_synth_opts->thread_stack; }diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c index 02df3e460489..4c9cca3acb6c 100644 --- a/tools/perf/util/intel-bts.c +++ b/tools/perf/util/intel-bts.c@@ -877,7 +877,7 @@ int intel_bts_process_auxtrace_info(union perf_event *event, bts->synth_opts = *session->itrace_synth_opts; } else { itrace_synth_opts__set_default(&bts->synth_opts, - session->itrace_synth_opts->default_no_sample); + session->itrace_synth_opts->default_no_sample, false); bts->synth_opts.thread_stack = session->itrace_synth_opts->thread_stack; }diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c index 9d6628169fd9..8c21c9f52d57 100644 --- a/tools/perf/util/intel-pt.c +++ b/tools/perf/util/intel-pt.c@@ -4463,7 +4463,8 @@ int intel_pt_process_auxtrace_info(union perf_event *event, } else { struct itrace_synth_opts *opts = session->itrace_synth_opts; - itrace_synth_opts__set_default(&pt->synth_opts, opts->default_no_sample); + itrace_synth_opts__set_default(&pt->synth_opts, + opts->default_no_sample, false); if (!opts->default_no_sample && !opts->inject) { pt->synth_opts.branches = false; pt->synth_opts.callchain = true;