v5 of the perf weight annotation patchkit

v5 of the perf weight annotation patchkit

[Andi Kleen]

Fixes the latest sashiko issues

[PATCH v5 1/4] perf tools record: Modernize -W man page

[Andi Kleen]

Modernize the -W / --weight description in the manpage to cover more
cases that are supported now.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 tools/perf/Documentation/perf-record.txt | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 178f483140ed..2c6510c5a87b 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -480,9 +480,11 @@ Note that this feature may not be available on all processors.
 
 -W::
 --weight::
-Enable weightened sampling. An additional weight is recorded per sample and can be
-displayed with the weight and local_weight sort keys.  This currently works for TSX
-abort events and some memory events in precise mode on modern Intel CPUs.
+Enable weighted sampling. One or more additional weights can be recorded per sample
+and can be displayed with the weight, weight2, weight3 and local_weight sort keys.
+Possible uses for weights are memory or instruction retirement latencies.
+Support depends on the PMU and the event, as well as its configuration. Typically
+it requires use of 'p'.
 
 --namespaces::
 Record events of type PERF_RECORD_NAMESPACES.  This enables 'cgroup_id' sort key.
-- 
2.55.0

Re: [PATCH v5 1/4] perf tools record: Modernize -W man page

[sashiko-bot]

> Modernize the -W / --weight description in the manpage to cover more
> cases that are supported now.
> 
> Signed-off-by: Andi Kleen <ak@linux.intel.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260830193459.2840519-1-ak@linux.intel.com?part=1

[PATCH v5 2/4] perf tools top: Add --weight option

[Andi Kleen]

Add a -W/--weight option to perf top to collect weights too. Useful with
follow on patches.

Assisted-by: omp:GPT-5.6-Luna
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 tools/perf/Documentation/perf-top.txt | 6 ++++++
 tools/perf/builtin-top.c              | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/tools/perf/Documentation/perf-top.txt b/tools/perf/Documentation/perf-top.txt
index af3e4230c72f..2da2a16bbf26 100644
--- a/tools/perf/Documentation/perf-top.txt
+++ b/tools/perf/Documentation/perf-top.txt
@@ -25,6 +25,12 @@ OPTIONS
 --count=<count>::
 	Event period to sample.
 
+-W::
+--weight::
+Enable weighted sampling. One or more additional weights can be recorded per sample
+and can be displayed with the weight, weight2, weight3 and local_weight sort keys.
+Possible uses for weights are memory or instruction retirement latencies.
+
 -C <cpu-list>::
 --cpu=<cpu>::
 Monitor only on the list of CPUs provided. Multiple CPUs can be provided as a
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 570410599f1b..2888ac3b7b92 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1493,6 +1493,8 @@ int cmd_top(int argc, const char **argv)
 	OPT_CALLBACK(0, "filter", &top.evlist, "filter",
 		     "event filter", parse_filter),
 	OPT_U64('c', "count", &opts->user_interval, "event period to sample"),
+	OPT_BOOLEAN('W', "weight", &opts->sample_weight,
+		    "sample by weight (on special events only)"),
 	OPT_STRING('p', "pid", &target->pid, "pid",
 		    "profile events on existing process id"),
 	OPT_STRING('t', "tid", &target->tid, "tid",
-- 
2.55.0

Re: [PATCH v5 2/4] perf tools top: Add --weight option

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:

Pre-existing issues:
- [High] Buffer overflow or NULL pointer dereference in for_each_drm_fdinfo_in_dir() due to unchecked reallocarray() failure.
- [High] Use-After-Free and memory leak in add_event() when strndup() fails.
--

commit f1674c1fafe728985095507f0cfd95caa7a7179c
Author: Andi Kleen <ak@linux.intel.com>

perf tools top: Add --weight option
    
Add a -W/--weight option to perf top to collect weights too. Useful with
follow on patches.

> diff --git a/tools/perf/Documentation/perf-top.txt b/tools/perf/Documentation/perf-top.txt
> index af3e4230c72f4..2da2a16bbf260 100644
> --- a/tools/perf/Documentation/perf-top.txt
> +++ b/tools/perf/Documentation/perf-top.txt
> @@ -25,6 +25,12 @@ OPTIONS
>  --count=<count>::
>  	Event period to sample.
>  
> +-W::
> +--weight::
> +Enable weighted sampling. One or more additional weights can be recorded per sample

[ ... ]

While reviewing this, I noticed some pre-existing issues in
tools/perf/util/drm_pmu.c:

tools/perf/util/drm_pmu.c:for_each_drm_fdinfo_in_dir() {
    ...
		if (minors->minors_num == minors->minors_len) {
			unsigned int *tmp = reallocarray(minors->minors, minors->minors_len + 4,
							 sizeof(unsigned int));

			if (tmp) {
				minors->minors = tmp;
				minors->minors_len += 4;
			}
		}
		minors->minors[minors->minors_num++] = minor;
    ...
}

[Severity: High]
This is a pre-existing issue, but does this code write out of bounds or
dereference a NULL pointer?

If reallocarray() fails, tmp is NULL, so minors->minors and minors->minors_len
are not updated.

However, the function proceeds to unconditionally assign minor to
minors->minors[minors->minors_num++].

If the array was initially NULL, this dereferences a NULL pointer. If it was
already allocated, this writes past the end of the un-resized buffer.


tools/perf/util/drm_pmu.c:add_event() {
    ...
	tmp = reallocarray(*events, *num_events + 1, sizeof(struct drm_pmu_event));
	if (!tmp)
		return -ENOMEM;
	tmp[*num_events].unit = unit;
	tmp[*num_events].desc = desc;
	tmp[*num_events].name = strndup(line, colon - line);
	if (!tmp[*num_events].name)
		return -ENOMEM;
	(*num_events)++;
	*events = tmp;
	return 0;
}

[Severity: High]
This is a pre-existing issue, but does this code leave a dangling pointer and
leak memory when strndup() fails?

If reallocarray() succeeds and moves the memory block, the old memory pointed
to by *events is freed.

If strndup() then fails, the function returns -ENOMEM without updating
*events to point to tmp.

This leaks the newly allocated tmp block and leaves *events as a dangling
pointer to the old, freed memory block.

Since the caller read_drm_pmus_cb() ignores the return value of add_event()
and continues parsing, a subsequent match could pass this dangling *events
pointer back into reallocarray(), triggering a use-after-free.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260830193459.2840519-1-ak@linux.intel.com?part=2

Re: [PATCH v5 2/4] perf tools top: Add --weight option

[Andi Kleen]

> 
> [Severity: High]
> This is a pre-existing issue, but does this code write out of bounds or
> dereference a NULL pointer?
> 
> If reallocarray() fails, tmp is NULL, so minors->minors and minors->minors_len
> are not updated.

OOM checking in user space is generally a folly anyways because if it
ever happens you're already in russian roulette with the OOM killer
killing you.

The right fix would be to use a xreallocarray that exits on error.

But it has nothing to do with these patches.

-Andi

[PATCH v5 3/4] perf tools: Add support for displaying weights in annotate

[Andi Kleen]

Add support for showing all the three possible per IP weights in
annotate. The weights are shown by defaults if any are non zero. This
is useful, especially with the new insn lat statistics, but also
for all the existing weights.

Add a hotkey to the interactive browser to turn them off (w), as well
as a perf annotate command line option.

The weights are stored unconditionally in the sym_hist_entry, which
will increase memory consumption somewhat.

Assisted-by: omp:GPT-5.6-Luna
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 tools/perf/Documentation/perf-annotate.txt |   3 +
 tools/perf/Documentation/perf-report.txt   |   6 +
 tools/perf/builtin-annotate.c              |   3 +
 tools/perf/builtin-report.c                |   3 +
 tools/perf/ui/browsers/annotate.c          |  20 +++-
 tools/perf/util/annotate.c                 | 121 +++++++++++++++++++--
 tools/perf/util/annotate.h                 |  44 +++++++-
 tools/perf/util/symbol_conf.h              |  13 ++-
 8 files changed, 194 insertions(+), 19 deletions(-)

diff --git a/tools/perf/Documentation/perf-annotate.txt b/tools/perf/Documentation/perf-annotate.txt
index a688738809c4..1a90b09a12d5 100644
--- a/tools/perf/Documentation/perf-annotate.txt
+++ b/tools/perf/Documentation/perf-annotate.txt
@@ -95,6 +95,9 @@ include::itrace.txt[]
 
 --gtk:: Use the GTK interface.
 
+--weights:: Show or hide (with `--no-weights`) weight columns in annotation output.
+	    By default, weight columns are shown when samples contain non-zero weights.
+
 -C::
 --cpu=<cpu>:: Only report samples for the list of CPUs provided. Multiple CPUs can
 	be provided as a comma-separated list with no space: 0,1. Ranges of
diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 22f87eaa3279..ae68ca402d0b 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -64,6 +64,9 @@ OPTIONS
 --symbol-filter=::
 	Only show symbols that match (partially) with this filter.
 
+--weights:: Show or hide (with `--no-weights`) weight columns in annotation output.
+	    By default, weight columns are shown when samples contain non-zero weights.
+
 -U::
 --hide-unresolved::
         Only display entries resolved to a symbol.
@@ -353,6 +356,9 @@ OPTIONS
 
 --gtk:: Use the GTK2 interface.
 
+--weights:: Show or hide (with `--no-weights`) weight columns in annotation output.
+           By default, weight columns are shown when samples contain non-zero weights.
+
 -k::
 --vmlinux=<file>::
         vmlinux pathname
diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index 69cb72b2082a..9e0b704c31f4 100644
--- a/tools/perf/builtin-annotate.c
+++ b/tools/perf/builtin-annotate.c
@@ -719,6 +719,8 @@ int cmd_annotate(int argc, const char **argv)
 	OPT_BOOLEAN(0, "tui", &annotate.use_tui, "Use the TUI interface"),
 #endif
 	OPT_BOOLEAN(0, "stdio", &annotate.use_stdio, "Use the stdio interface"),
+	OPT_BOOLEAN(0, "weights", &symbol_conf.annotate_weight,
+		    "Show or hide weight columns in annotation. Default show if non zero."),
 	OPT_BOOLEAN(0, "stdio2", &annotate.use_stdio2, "Use the stdio interface"),
 	OPT_BOOLEAN(0, "ignore-vmlinux", &symbol_conf.ignore_vmlinux,
                     "don't load vmlinux even if found"),
@@ -788,6 +790,7 @@ int cmd_annotate(int argc, const char **argv)
 
 	set_option_flag(options, 0, "show-total-period", PARSE_OPT_EXCLUSIVE);
 	set_option_flag(options, 0, "show-nr-samples", PARSE_OPT_EXCLUSIVE);
+	symbol_conf.annotate_weight = true;
 
 	annotation_options__init();
 
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 60d1f166629e..b55c01bb45b4 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -1364,6 +1364,8 @@ int cmd_report(int argc, const char **argv)
 #endif
 	OPT_BOOLEAN(0, "stdio", &report.use_stdio,
 		    "Use the stdio interface"),
+	OPT_BOOLEAN(0, "weights", &symbol_conf.annotate_weight,
+			"Show or hide weight columns in annotation. Default show if non-zero."),
 	OPT_BOOLEAN(0, "header", &report.header, "Show data header."),
 	OPT_BOOLEAN(0, "header-only", &report.header_only,
 		    "Show only data header."),
@@ -1525,6 +1527,7 @@ int cmd_report(int argc, const char **argv)
 	 * reference exited threads.
 	 */
 	symbol_conf.keep_exited_threads = true;
+	symbol_conf.annotate_weight = true;
 
 	annotation_options__init();
 
diff --git a/tools/perf/ui/browsers/annotate.c b/tools/perf/ui/browsers/annotate.c
index e47a46775089..e8de644c0e9d 100644
--- a/tools/perf/ui/browsers/annotate.c
+++ b/tools/perf/ui/browsers/annotate.c
@@ -189,7 +189,7 @@ static void annotate_browser__draw_current_jump(struct ui_browser *browser)
 	struct map_symbol *ms = ab->b.priv;
 	struct symbol *sym = ms->sym;
 	struct annotation *notes = symbol__annotation(sym);
-	u8 pcnt_width = annotation__pcnt_width(notes);
+	u8 pcnt_width = annotation__pcnt_width(notes, ab->evsel);
 	u8 cntr_width = annotation__br_cntr_width();
 	int width;
 	int diff = 0;
@@ -255,7 +255,8 @@ static unsigned int annotate_browser__refresh(struct ui_browser *browser)
 {
 	struct annotation *notes = browser__annotation(browser);
 	int ret = ui_browser__list_head_refresh(browser);
-	int pcnt_width = annotation__pcnt_width(notes);
+	int pcnt_width = annotation__pcnt_width(notes,
+		container_of(browser, struct annotate_browser, b)->evsel);
 
 	if (annotate_opts.jump_arrows)
 		annotate_browser__draw_current_jump(browser);
@@ -972,6 +973,7 @@ static int annotate_browser__run(struct annotate_browser *browser,
 		"O             Bump offset level (jump targets -> +call -> all -> cycle thru)\n"
 		"s             Toggle source code view\n"
 		"t             Circulate percent, total period, samples view\n"
+		"w             Toggle weight columns\n"
 		"c             Show min/max cycle\n"
 		"/             Search string\n"
 		"k             Toggle line numbers\n"
@@ -1091,6 +1093,14 @@ static int annotate_browser__run(struct annotate_browser *browser,
 				symbol_conf.show_total_period = true;
 			annotation__update_column_widths(notes);
 			continue;
+		case 'w':
+			symbol_conf.annotate_weight = !symbol_conf.annotate_weight;
+			browser->b.width = notes->src->widths.max_line_len +
+					   annotation__pcnt_width(notes, evsel) +
+					   annotation__cycles_width(notes) +
+					   annotation__br_cntr_width();
+			ui_browser__refresh_dimensions(&browser->b);
+			continue;
 		case 'c':
 			if (annotate_opts.show_minmax_cycle)
 				annotate_opts.show_minmax_cycle = false;
@@ -1225,10 +1235,12 @@ int __hist_entry__tui_annotate(struct hist_entry *he, struct map_symbol *ms,
 		browser.type_hash = hashmap__new(type_hash, type_equal, /*ctx=*/NULL);
 	}
 
-	browser.b.width = notes->src->widths.max_line_len;
+	browser.b.width = notes->src->widths.max_line_len +
+			   annotation__pcnt_width(notes, evsel) +
+			   annotation__cycles_width(notes) +
+			   annotation__br_cntr_width();
 	browser.b.nr_entries = notes->src->nr_entries;
 	browser.b.entries = &notes->src->source;
-	browser.b.width += 18; /* Percentage */
 
 	if (annotate_opts.hide_src_code)
 		ui_browser__init_asm_mode(&browser.b);
diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index df70e95a8470..9304c21c686a 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -222,6 +222,7 @@ static int __symbol__inc_addr_samples(struct map_symbol *ms,
 	u64 offset;
 	struct sym_hist *h;
 	struct sym_hist_entry *entry;
+	u64 weight = sample->weight ?: sample->ins_lat ?: sample->weight3;
 
 	pr_debug3("%s: addr=%#" PRIx64 "\n", __func__, map__unmap_ip(ms->map, addr));
 
@@ -256,10 +257,28 @@ static int __symbol__inc_addr_samples(struct map_symbol *ms,
 	entry->nr_samples++;
 	entry->period += sample->period;
 
+	if (sample->evsel->core.attr.sample_type & PERF_SAMPLE_WEIGHT_TYPE) {
+		entry->weight_sum[WEIGHT_WEIGHT] += sample->weight;
+		entry->weight_num[WEIGHT_WEIGHT]++;
+		if (sample->weight)
+			sym_hist__set_weight_mask(h, BIT(WEIGHT_WEIGHT));
+	}
+	if (sample->evsel->core.attr.sample_type & PERF_SAMPLE_WEIGHT_STRUCT) {
+		entry->weight_sum[WEIGHT_INSNLAT] += sample->ins_lat;
+		entry->weight_num[WEIGHT_INSNLAT]++;
+		entry->weight_sum[WEIGHT_WEIGHT3] += sample->weight3;
+		entry->weight_num[WEIGHT_WEIGHT3]++;
+		if (sample->ins_lat)
+			sym_hist__set_weight_mask(h, BIT(WEIGHT_INSNLAT));
+		if (sample->weight3)
+			sym_hist__set_weight_mask(h, BIT(WEIGHT_WEIGHT3));
+	}
+
 	pr_debug3("%#" PRIx64 " %s: period++ [addr: %#" PRIx64 ", %#" PRIx64
-		  ", evidx=%d] => nr_samples: %" PRIu64 ", period: %" PRIu64 "\n",
+		  ", evidx=%d] => nr_samples: %" PRIu64 ", period: %" PRIu64
+		  " weight %" PRIu64 "\n",
 		  sym->start, sym->name, addr, addr - sym->start, evsel->core.idx,
-		  entry->nr_samples, entry->period);
+		  entry->nr_samples, entry->period, weight);
 	return 0;
 }
 
@@ -778,6 +797,50 @@ static bool needs_type_info(struct annotated_data_type *data_type)
 	return (data_type != &stackop_type) && (data_type != &canary_type);
 }
 
+static const char *annotation__weight_mode_str(enum symbol__weight_mode mode,
+						 const struct evsel *evsel)
+{
+	switch (mode) {
+	case WEIGHT_NONE:
+		return "";
+	case WEIGHT_WEIGHT:
+		return "Weight";
+	case WEIGHT_INSNLAT:
+		return "InsnLat";
+	case WEIGHT_WEIGHT3:
+		switch (evsel__e_machine((struct evsel *)evsel, NULL)) {
+		case EM_PPC:
+		case EM_PPC64:
+			return "PCycleLat";
+		case EM_X86_64:
+			return "RetireLat";
+		default:
+			return "Weight3";
+		}
+	default:
+		return "";
+	}
+}
+
+static void annotation__column_title(char *buf, size_t size,
+					     struct annotation *notes,
+					     const struct evsel *evsel)
+{
+	const char *base = symbol_conf.show_total_period ? "Period" :
+			symbol_conf.show_nr_samples ? "Samples" : "Percent";
+	int weight;
+	u8 weight_mask = annotation__weight_mask(notes, evsel);
+
+	scnprintf(buf, size, "%s", base);
+	for_each_weight(weight) {
+		if (weight_mask & BIT(weight))
+			scnprintf(buf + strlen(buf),
+				  size - strlen(buf),
+				  " %s",
+				  annotation__weight_mode_str(weight, evsel));
+	}
+}
+
 static int
 annotation_line__print(struct annotation_line *al, struct annotation_print_data *apd,
 		       struct annotation_options *opts, int printed,
@@ -833,6 +896,8 @@ annotation_line__print(struct annotation_line *al, struct annotation_print_data
 		for (i = 0; i < nr_percent; i++) {
 			struct annotation_data *data = &al->data[i];
 			double percent;
+			int weight;
+			u8 weight_mask = annotation__weight_mask(notes, apd->evsel);
 
 			percent = annotation_data__percent(data, percent_type);
 			color = get_percent_color(percent);
@@ -845,6 +910,14 @@ annotation_line__print(struct annotation_line *al, struct annotation_print_data
 					      data->he.nr_samples);
 			else
 				color_fprintf(stdout, color, " %7.2f", percent);
+			for_each_weight(weight) {
+				if (weight_mask & BIT(weight))
+					color_fprintf(stdout, color, " %7" PRIu64,
+						      data->he.weight_num[weight] ?
+						      data->he.weight_sum[weight] /
+						      data->he.weight_num[weight]
+						      : 0);
+			}
 		}
 
 		printf(" : ");
@@ -891,7 +964,7 @@ annotation_line__print(struct annotation_line *al, struct annotation_print_data
 	} else if (max_lines && printed >= max_lines)
 		return 1;
 	else {
-		int width = annotation__pcnt_width(notes);
+		int width = annotation__pcnt_width(notes, apd->evsel);
 
 		if (queue)
 			return -1;
@@ -915,6 +988,9 @@ static void calc_percent(struct annotation *notes,
 	struct sym_hist *sym_hist = annotation__histogram(notes, evsel);
 	unsigned int hits = 0;
 	u64 period = 0;
+	int i;
+	u64 weight_sum[WEIGHT_WEIGHT3 + 1] = { 0 };
+	u64 weight_num[WEIGHT_WEIGHT3 + 1] = { 0 };
 
 	while (offset < end) {
 		struct sym_hist_entry *entry;
@@ -923,6 +999,10 @@ static void calc_percent(struct annotation *notes,
 		if (entry) {
 			hits   += entry->nr_samples;
 			period += entry->period;
+			for_each_weight(i) {
+				weight_sum[i] += entry->weight_sum[i];
+				weight_num[i] += entry->weight_num[i];
+			}
 		}
 		++offset;
 	}
@@ -930,6 +1010,10 @@ static void calc_percent(struct annotation *notes,
 	if (sym_hist->nr_samples) {
 		data->he.period     = period;
 		data->he.nr_samples = hits;
+		for_each_weight(i) {
+			data->he.weight_sum[i] = weight_sum[i];
+			data->he.weight_num[i] = weight_num[i];
+		}
 		data->percent[PERCENT_HITS_LOCAL] = 100.0 * hits / sym_hist->nr_samples;
 	}
 
@@ -1252,8 +1336,9 @@ int hist_entry__annotate_printf(struct hist_entry *he, struct evsel *evsel)
 	int printed = 2, queue_len = 0;
 	int more = 0;
 	bool context = opts->context;
-	int width = annotation__pcnt_width(notes);
+	int width = annotation__pcnt_width(notes, evsel);
 	int graph_dotted_len;
+	char title[64];
 	char buf[512];
 
 	filename = strdup(dso__long_name(dso));
@@ -1275,10 +1360,10 @@ int hist_entry__annotate_printf(struct hist_entry *he, struct evsel *evsel)
 		return ENOTSUP;
 	}
 
-	graph_dotted_len = printf(" %-*.*s|	Source code & Disassembly of %s for %s (%" PRIu64 " samples, "
+	annotation__column_title(title, sizeof(title), notes, evsel);
+	graph_dotted_len = printf(" %-*.*s|\tSource code & Disassembly of %s for %s (%" PRIu64 " samples, "
 				  "percent: %s)\n",
-				  width, width, symbol_conf.show_total_period ? "Period" :
-				  symbol_conf.show_nr_samples ? "Samples" : "Percent",
+				  width, width, title,
 				  d_filename, evsel_name, h->nr_samples,
 				  percent_type_str(opts->percent_type));
 
@@ -2029,7 +2114,8 @@ static int disasm_line__snprint_type_info(struct disasm_line *dl,
 	return printed;
 }
 
-void annotation_line__write(struct annotation_line *al, struct annotation *notes,
+void annotation_line__write(struct annotation_line *al,
+			    struct annotation *notes,
 			    const struct annotation_write_ops *wops,
 			    struct annotation_print_data *apd)
 {
@@ -2037,7 +2123,8 @@ void annotation_line__write(struct annotation_line *al, struct annotation *notes
 	bool change_color = wops->change_color;
 	double percent_max = annotation_line__max_percent(al, annotate_opts.percent_type);
 	int width = wops->width;
-	int pcnt_width = annotation__pcnt_width(notes);
+	int pcnt_width = annotation__pcnt_width(notes, apd->evsel);
+	u8 weight_mask = annotation__weight_mask(notes, apd->evsel);
 	int cycles_width = annotation__cycles_width(notes);
 	bool show_title = false;
 	char bf[256];
@@ -2062,6 +2149,7 @@ void annotation_line__write(struct annotation_line *al, struct annotation *notes
 
 		for (i = 0; i < al->data_nr; i++) {
 			double percent;
+			int weight;
 
 			percent = annotation_data__percent(&al->data[i],
 							   annotate_opts.percent_type);
@@ -2075,6 +2163,15 @@ void annotation_line__write(struct annotation_line *al, struct annotation *notes
 			} else {
 				obj__printf(obj, "%7.2f ", percent);
 			}
+
+			for_each_weight(weight) {
+				if (weight_mask & BIT(weight))
+					obj__printf(obj, "%7" PRIu64 " ",
+						    al->data[i].he.weight_num[weight] ?
+						    al->data[i].he.weight_sum[weight] /
+						    al->data[i].he.weight_num[weight] :
+						    0);
+			}
 		}
 	} else {
 		obj__set_percent_color(obj, 0, current_entry);
@@ -2082,9 +2179,9 @@ void annotation_line__write(struct annotation_line *al, struct annotation *notes
 		if (!show_title)
 			obj__printf(obj, "%-*s", pcnt_width, " ");
 		else {
-			obj__printf(obj, "%-*s", pcnt_width,
-					   symbol_conf.show_total_period ? "Period" :
-					   symbol_conf.show_nr_samples ? "Samples" : "Percent");
+			char buf[64];
+			annotation__column_title(buf, sizeof(buf), notes, apd->evsel);
+			obj__printf(obj, "%-*s", pcnt_width, buf);
 		}
 	}
 	width -= pcnt_width;
diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h
index fa08d09b80f7..d7807df6667f 100644
--- a/tools/perf/util/annotate.h
+++ b/tools/perf/util/annotate.h
@@ -6,6 +6,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <linux/types.h>
+#include <linux/bitops.h>
 #include <linux/list.h>
 #include <linux/rbtree.h>
 #include <asm/bug.h>
@@ -86,6 +87,8 @@ struct annotation;
 struct sym_hist_entry {
 	u64		nr_samples;
 	u64		period;
+	u64		weight_sum[WEIGHT_WEIGHT3 + 1];
+	u64		weight_num[WEIGHT_WEIGHT3 + 1];
 };
 
 enum {
@@ -231,8 +234,20 @@ void symbol__calc_percent(struct symbol *sym, struct evsel *evsel);
 struct sym_hist {
 	u64		      nr_samples;
 	u64		      period;
+	u8		      weight_mask;
 };
 
+/* Can be set asynchronously by top. */
+static inline u8 sym_hist__weight_mask(const struct sym_hist *hist)
+{
+	return __atomic_load_n(&hist->weight_mask, __ATOMIC_RELAXED);
+}
+
+static inline void sym_hist__set_weight_mask(struct sym_hist *hist, u8 mask)
+{
+	__atomic_fetch_or(&hist->weight_mask, mask, __ATOMIC_RELAXED);
+}
+
 /**
  * struct cyc_hist - (CPU) cycle histogram for a basic block
  *
@@ -376,9 +391,34 @@ static inline int annotation__cycles_width(struct annotation *notes)
 	return notes->branch ? ANNOTATION__IPC_WIDTH + ANNOTATION__CYCLES_WIDTH : 0;
 }
 
-static inline int annotation__pcnt_width(struct annotation *notes)
+static inline u8 annotation__weight_mask(struct annotation *notes,
+					 const struct evsel *evsel)
+{
+	u8 mask = 0;
+	struct evsel *pos;
+	int i;
+
+	if (!symbol_conf.annotate_weight)
+		return 0;
+
+	if (evsel__is_group_event((struct evsel *)evsel)) {
+		pos = (struct evsel *)evsel;
+		for (i = 0; i < evsel->core.nr_members; i++) {
+			mask |= sym_hist__weight_mask(&notes->src->histograms[pos->core.idx]);
+			pos = evsel__next(pos);
+		}
+		return mask;
+	}
+
+	return sym_hist__weight_mask(&notes->src->histograms[evsel->core.idx]);
+}
+
+static inline int annotation__pcnt_width(struct annotation *notes,
+					 const struct evsel *evsel)
 {
-	return (symbol_conf.show_total_period ? 12 : 8) * notes->src->nr_events;
+	int extra = hweight8(annotation__weight_mask(notes, evsel)) * 8;
+	return ((symbol_conf.show_total_period ? 12 : 8) + extra) *
+	       notes->src->nr_events;
 }
 
 static inline bool annotation_line__filter(struct annotation_line *al)
diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h
index 0dee5aa6a534..71f60081a85b 100644
--- a/tools/perf/util/symbol_conf.h
+++ b/tools/perf/util/symbol_conf.h
@@ -27,6 +27,16 @@ enum a2l_style {
 };
 #define MAX_A2L_STYLE (A2L_STYLE_CMD + 1)
 
+enum symbol__weight_mode {
+	WEIGHT_NONE = 0,
+	WEIGHT_WEIGHT,
+	WEIGHT_INSNLAT,
+	WEIGHT_WEIGHT3,
+};
+
+#define for_each_weight(_weight) \
+	for ((_weight) = WEIGHT_WEIGHT; (_weight) <= WEIGHT_WEIGHT3; (_weight)++)
+
 struct symbol_conf {
 	bool		nanosecs;
 	unsigned short	priv_size;
@@ -69,7 +79,8 @@ struct symbol_conf {
 			annotate_data_sample,
 			skip_empty,
 			enable_latency,
-			prefer_latency;
+			prefer_latency,
+			annotate_weight;
 	const char	*vmlinux_name,
 			*kallsyms_name,
 			*source_prefix,
-- 
2.55.0

Re: [PATCH v5 3/4] perf tools: Add support for displaying weights in annotate

[sashiko-bot]

> Add support for showing all the three possible per IP weights in
> annotate. The weights are shown by defaults if any are non zero. This
> is useful, especially with the new insn lat statistics, but also
> for all the existing weights.
> 
> Add a hotkey to the interactive browser to turn them off (w), as well
> as a perf annotate command line option.
> 
> The weights are stored unconditionally in the sym_hist_entry, which
> will increase memory consumption somewhat.
> 
> Assisted-by: omp:GPT-5.6-Luna
> Signed-off-by: Andi Kleen <ak@linux.intel.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260830193459.2840519-1-ak@linux.intel.com?part=3

[PATCH v5 4/4] perf tools: Add test for weight annotation

[Andi Kleen]

Add a test case to check if --stdio weight annotation works

Assisted-by: omp:GPT-5.6-Luna
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 tools/perf/tests/shell/annotate_weight.sh | 63 +++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100755 tools/perf/tests/shell/annotate_weight.sh

diff --git a/tools/perf/tests/shell/annotate_weight.sh b/tools/perf/tests/shell/annotate_weight.sh
new file mode 100755
index 000000000000..6b8c105c048b
--- /dev/null
+++ b/tools/perf/tests/shell/annotate_weight.sh
@@ -0,0 +1,63 @@
+#!/bin/bash
+# perf annotate weight regression test
+# SPDX-License-Identifier: GPL-2.0
+
+set -e
+
+shelldir=$(dirname "$0")
+# shellcheck source=tools/perf/tests/shell/lib/perf_has_symbol.sh
+. "${shelldir}"/lib/perf_has_symbol.sh
+
+testsym="test_loop"
+skip_test_missing_symbol "${testsym}"
+
+perfdata=$(mktemp /tmp/__perf_test.annotate_weight.XXXXX)
+record_log=$(mktemp /tmp/__perf_test.annotate_weight.XXXXX.log)
+report_out=$(mktemp /tmp/__perf_test.annotate_weight.XXXXX.report)
+annotate_out=$(mktemp /tmp/__perf_test.annotate_weight.XXXXX.annotate)
+
+cleanup() {
+	rm -f "${perfdata}" "${record_log}" "${report_out}" "${annotate_out}"
+	trap - EXIT TERM INT
+}
+
+trap 'cleanup; exit 1' TERM INT
+trap cleanup EXIT
+
+# mem-loads:pu requests a precise user PEBS event whose sample weight should
+# be populated by -W. Unsupported PEBS/weight PMUs are skipped below.
+if ! perf record -W -e mem-loads:pu -o "${perfdata}" -- perf test -w thloop \
+	> /dev/null 2> "${record_log}"; then
+	echo "[SKIP] precise PEBS weight sampling is unavailable"
+	exit 2
+fi
+
+# Confirm the PMU actually produced nonzero weights. A successful record alone
+# is insufficient: some PMUs accept the event but provide no weight payload.
+if ! perf report --stdio -i "${perfdata}" --fields=weight1,weight2,weight3,symbol --percent-limit 0 \
+	> "${report_out}" 2> "${record_log}"; then
+	echo "[SKIP] weighted samples cannot be decoded"
+	exit 2
+fi
+
+if ! awk '$1 ~ /^[0-9]/ && ($1 + 0) > 0 { found = 1 } END { exit !found }' \
+	"${report_out}"; then
+	echo "[SKIP] PEBS weight sampling produced no nonzero weights"
+	exit 2
+fi
+
+perf annotate --stdio -i "${perfdata}" --symbol "${testsym}" \
+	> "${annotate_out}" 2> "${record_log}"
+
+grep -q 'Percent Weight' "${annotate_out}"
+
+# The second numeric column is the rendered average weight. This assertion
+# fails on the original regression because calc_percent() left it at zero.
+if ! awk '$1 ~ /^[0-9]/ && $2 ~ /^[0-9]/ && ($2 + 0) > 0 { found = 1 } END { exit !found }' \
+	"${annotate_out}"; then
+	echo "Annotation output contained no nonzero weight"
+	cat "${annotate_out}"
+	exit 1
+fi
+
+echo "PEBS annotation weights: PASS"
-- 
2.55.0

Re: [PATCH v5 4/4] perf tools: Add test for weight annotation

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The script conflates PEBS support checking with workload execution, masking workload failures as skipped tests.
- [Medium] Silent test failure due to unhandled `grep -q` execution under `set -e`.
--

commit 8db1611c3b92cee56576e6157914227faf90fc5a
Author: Andi Kleen <ak@linux.intel.com>

perf tools: Add test for weight annotation

This commit adds a shell script test case to check if the --stdio weight
annotation functions correctly in perf annotate.

> diff --git a/tools/perf/tests/shell/annotate_weight.sh b/tools/perf/tests/shell/annotate_weight.sh
> new file mode 100755
> index 0000000000000..6b8c105c048b5
> --- /dev/null
> +++ b/tools/perf/tests/shell/annotate_weight.sh
[ ... ]
> +trap 'cleanup; exit 1' TERM INT
> +trap cleanup EXIT
> +
> +# mem-loads:pu requests a precise user PEBS event whose sample weight should
> +# be populated by -W. Unsupported PEBS/weight PMUs are skipped below.
> +if ! perf record -W -e mem-loads:pu -o "${perfdata}" -- perf test -w thloop \
> +	> /dev/null 2> "${record_log}"; then
> +	echo "[SKIP] precise PEBS weight sampling is unavailable"
> +	exit 2
> +fi

[Severity: Medium]
If the inner workload (perf test -w thloop) crashes or otherwise fails to
execute, does this conditional block improperly catch the failure and report 
it as an unsupported hardware feature? 

It looks like any non-zero exit status from the child process will result 
in a skipped test, which might mask underlying environment or test suite bugs.

[ ... ]
> +	echo "[SKIP] PEBS weight sampling produced no nonzero weights"
> +	exit 2
> +fi
> +
> +perf annotate --stdio -i "${perfdata}" --symbol "${testsym}" \
> +	> "${annotate_out}" 2> "${record_log}"
> +
> +grep -q 'Percent Weight' "${annotate_out}"

[Severity: Medium]
Since set -e is enabled at the top of the script, will this isolated grep 
command cause an abrupt and silent exit if the 'Percent Weight' header is 
missing from the annotation output? 

If the string is missing, grep will exit with code 1, which might instantly 
abort the script without printing diagnostic output, making regressions harder 
to debug.

> +
> +# The second numeric column is the rendered average weight. This assertion
[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260830193459.2840519-1-ak@linux.intel.com?part=4

Re: [PATCH v5 4/4] perf tools: Add test for weight annotation

[Andi Kleen]

> > +# mem-loads:pu requests a precise user PEBS event whose sample weight should
> > +# be populated by -W. Unsupported PEBS/weight PMUs are skipped below.
> > +if ! perf record -W -e mem-loads:pu -o "${perfdata}" -- perf test -w thloop \
> > +	> /dev/null 2> "${record_log}"; then
> > +	echo "[SKIP] precise PEBS weight sampling is unavailable"
> > +	exit 2
> > +fi
> 
> [Severity: Medium]
> If the inner workload (perf test -w thloop) crashes or otherwise fails to
> execute, does this conditional block improperly catch the failure and report 
> it as an unsupported hardware feature? 
> 
> It looks like any non-zero exit status from the child process will result 
> in a skipped test, which might mask underlying environment or test suite bugs.


There are other tests for this, so this is acceptable.

> 
> [ ... ]
> > +	echo "[SKIP] PEBS weight sampling produced no nonzero weights"
> > +	exit 2
> > +fi
> > +
> > +perf annotate --stdio -i "${perfdata}" --symbol "${testsym}" \
> > +	> "${annotate_out}" 2> "${record_log}"
> > +
> > +grep -q 'Percent Weight' "${annotate_out}"
> 
> [Severity: Medium]
> Since set -e is enabled at the top of the script, will this isolated grep 
> command cause an abrupt and silent exit if the 'Percent Weight' header is 
> missing from the annotation output? 
> 
> If the string is missing, grep will exit with code 1, which might instantly 
> abort the script without printing diagnostic output, making regressions harder 
> to debug.

it will exit with 1 which makes perf test fail I believe.




-Andi

Re: v5 of the perf weight annotation patchkit

[Namhyung Kim]

On Sun, Aug 30, 2026 at 12:34:36PM -0700, Andi Kleen wrote:
> Fixes the latest sashiko issues
> 

Reviewed-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung