perf tools: Expose opt-in --hybrid-merge

Add --hybrid-merge to perf report and perf top. It merges the events a
wildcard expanded to across the core PMUs, and their histograms, so
that a symbol which ran on more than one kind of core is reported once
with the total rather than once per PMU.

evlist__merge_hybrid() links the events and evlist__merge_hists_hybrid()
links the histograms. There is nothing to merge on a machine with a
single core PMU, or when the events didn't come from a wildcard, so
warn in that case rather than quietly producing an unmerged report.

Merging collapses the per-PMU entries into one set, which doesn't
combine with the per-level breakdown of --hierarchy, so asking for both
is an error.

Signed-off-by: Ian Rogers <irogers@google.com>
Assisted-by: Antigravity:gemini-3.1-pro
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-report.txt

@@ -578,6 +578,11 @@ include::itrace.txt[]
 --raw-trace::
 	When displaying traceevent output, do not use print fmt or plugins.
 
+--hybrid-merge::
+	Merge matching events from all hybrid core PMUs into one
+	display. For example, if a wildcard expands to run on both p-cores and
+	e-cores, this aggregates them into a single view.
+
 -H::
 --hierarchy::
 	Enable hierarchical output.  In the hierarchy mode, each sort key groups

tools/perf/Documentation/perf-top.txt

@@ -49,6 +49,11 @@ Default is to monitor all CPUS.
 	encoding with the layout of the event control registers as described
 	by entries in /sys/bus/event_source/devices/cpu/format/*.
 
+--hybrid-merge::
+	Merge matching events from all hybrid core PMUs into one
+	display. For example, if a wildcard expands to run on both p-cores and
+	e-cores, this aggregates them into a single view.
+
 --filter=<filter>::
 	Event filter.  This option should follow an event selector (-e). For
 	syntax see linkperf:perf-record[1].

tools/perf/builtin-report.c

@@ -1114,6 +1114,17 @@ static int __cmd_report(struct report *rep)
 	evlist__for_each_entry(session->evlist, pos)
 		rep->nr_entries += evsel__hists(pos)->nr_entries;
 
+	if (symbol_conf.hybrid_merge) {
+		struct perf_env *env = perf_session__env(session);
+
+		if (evlist__can_merge_hybrid(session->evlist, env)) {
+			evlist__merge_hybrid(session->evlist, env);
+			evlist__merge_hists_hybrid(session->evlist, false);
+		} else {
+			ui__warning("--hybrid-merge: no events to merge across core PMUs\n");
+		}
+	}
+
 	if (use_browser == 0) {
 		if (verbose > 3)
 			perf_session__fprintf(session, stdout);
@@ -1449,6 +1460,8 @@ int cmd_report(int argc, const char **argv)
 		    parse_branch_mode),
 	OPT_BOOLEAN(0, "branch-history", &branch_call_mode,
 		    "add last branch records to call history"),
+	OPT_BOOLEAN(0, "hybrid-merge", &symbol_conf.hybrid_merge,
+		    "merge the same event across hybrid core PMUs"),
 	OPT_STRING(0, "objdump", &objdump_path, "path",
 		   "objdump binary to use for disassembly and annotations"),
 	OPT_STRING(0, "addr2line", &addr2line_path, "path",
@@ -1548,6 +1561,12 @@ int cmd_report(int argc, const char **argv)
 		report.symbol_filter_str = argv[0];
 	}
 
+	if (symbol_conf.report_hierarchy && symbol_conf.hybrid_merge) {
+		pr_err("Error: --hierarchy and --hybrid-merge are mutually exclusive.\n");
+		ret = -EINVAL;
+		goto exit;
+	}
+
 	if (disassembler_style) {
 		annotate_opts.disassembler_style = strdup(disassembler_style);
 		if (!annotate_opts.disassembler_style)

tools/perf/builtin-top.c

@@ -1336,6 +1336,15 @@ static int __cmd_top(struct perf_top *top)
         if (!target__none(&opts->target))
 		evlist__enable(top->evlist);
 
+	if (symbol_conf.hybrid_merge) {
+		if (evlist__can_merge_hybrid(top->evlist, /*env=*/NULL)) {
+			evlist__merge_hybrid(top->evlist, /*env=*/NULL);
+			evlist__merge_hists_hybrid(top->evlist, false);
+		} else {
+			ui__warning("--hybrid-merge: no events to merge across core PMUs\n");
+		}
+	}
+
 	ret = -1;
 	if (pthread_create(&thread_process, NULL, process_thread, top)) {
 		ui__error("Could not create process thread.\n");
@@ -1491,6 +1500,8 @@ int cmd_top(int argc, const char **argv)
 	OPT_CALLBACK('e', "event", &parse_events_option_args, "event",
 		     "event selector. use 'perf list' to list available events",
 		     parse_events_option),
+	OPT_BOOLEAN(0, "hybrid-merge", &symbol_conf.hybrid_merge,
+		    "merge the same event across hybrid core PMUs"),
 	OPT_CALLBACK(0, "filter", &top.evlist, "filter",
 		     "event filter", parse_filter),
 	OPT_U64('c', "count", &opts->user_interval, "event period to sample"),
@@ -1679,6 +1690,12 @@ int cmd_top(int argc, const char **argv)
 	if (argc)
 		usage_with_options(top_usage, options);
 
+	if (symbol_conf.report_hierarchy && symbol_conf.hybrid_merge) {
+		pr_err("Error: --hierarchy and --hybrid-merge are mutually exclusive.\n");
+		status = -EINVAL;
+		goto out_put_evlist;
+	}
+
 	if (disassembler_style) {
 		annotate_opts.disassembler_style = strdup(disassembler_style);
 		if (!annotate_opts.disassembler_style) {

tools/perf/util/symbol.c

@@ -73,6 +73,7 @@ struct symbol_conf symbol_conf = {
 	.symfs			= "",
 	.symfs_layout_flat	= false,
 	.event_group		= true,
+	.hybrid_merge		= false,
 	.inline_name		= true,
 	.res_sample		= 0,
 	.addr2line_timeout_ms	= 5 * 1000,