perf stat: Remove print_mixed_hw_group_error

print_mixed_hw_group_error will print a warning when a group of events
uses different PMUs.

This isn't possible to happen as parse_events__sort_events_and_fix_groups()
will break groups when this happens, adding the warning at the start
of perf of:

  WARNING: events were regrouped to match PMUs

As the previous mixed group warning can never happen, remove the
associated code.

Committer testing:

Before/after:

  acme@five:~$ perf stat -e '{cpu_core/cycles/,cpu_atom/cycles/}' sleep 1
  WARNING: events were regrouped to match PMUs

   Performance counter stats for 'sleep 1':

             424,895      cpu_atom/cycles/u
       <not counted>      cpu_core/cycles/u         (0.00%)

         1.011862314 seconds time elapsed

         0.000000000 seconds user
         0.003166000 seconds sys

  acme@five:~$

Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dominique Martinet <asmadeus@codewreck.org>
Cc: Dr. David Alan Gilbert <linux@treblig.org>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Levi Yun <yeoreum.yun@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Weilin Wang <weilin.wang@intel.com>
Link: https://lore.kernel.org/r/20250402201549.4090305-3-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 0 insertions, 32 deletions

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index 1115efb380fb..aab3697aed63 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -798,30 +798,6 @@ static void abs_printout(struct perf_stat_config *config,
 	print_cgroup(config, os, evsel->cgrp);
 }
 
-static bool is_mixed_hw_group(struct evsel *counter)
-{
-	struct evlist *evlist = counter->evlist;
-	u32 pmu_type = counter->core.attr.type;
-	struct evsel *pos;
-
-	if (counter->core.nr_members < 2)
-		return false;
-
-	evlist__for_each_entry(evlist, pos) {
-		/* software events can be part of any hardware group */
-		if (pos->core.attr.type == PERF_TYPE_SOFTWARE)
-			continue;
-		if (pmu_type == PERF_TYPE_SOFTWARE) {
-			pmu_type = pos->core.attr.type;
-			continue;
-		}
-		if (pmu_type != pos->core.attr.type)
-			return true;
-	}
-
-	return false;
-}
-
 static bool evlist__has_hybrid_pmus(struct evlist *evlist)
 {
 	struct evsel *evsel;
@@ -886,8 +862,6 @@ static void printout(struct perf_stat_config *config, struct outstate *os,
 		if (counter->supported) {
 			if (!evlist__has_hybrid_pmus(counter->evlist)) {
 				config->print_free_counters_hint = 1;
-				if (is_mixed_hw_group(counter))
-					config->print_mixed_hw_group_error = 1;
 			}
 		}
 	}
@@ -1587,11 +1561,6 @@ static void print_footer(struct perf_stat_config *config)
 "	echo 0 > /proc/sys/kernel/nmi_watchdog\n"
 "	perf stat ...\n"
 "	echo 1 > /proc/sys/kernel/nmi_watchdog\n");
-
-	if (config->print_mixed_hw_group_error)
-		fprintf(output,
-			"The events in group usually have to be from "
-			"the same PMU. Try reorganizing the group.\n");
 }
 
 static void print_percore(struct perf_stat_config *config,
diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
index 2fda9acd7374..1bcd7634bf47 100644
--- a/tools/perf/util/stat.h
+++ b/tools/perf/util/stat.h
@@ -100,7 +100,6 @@ struct perf_stat_config {
 	int			 times;
 	int			 run_count;
 	int			 print_free_counters_hint;
-	int			 print_mixed_hw_group_error;
 	const char		*csv_sep;
 	struct stats		*walltime_nsecs_stats;
 	struct rusage		 ru_data;