[PATCH 4/4] perf hist: Honor symbol_conf.skip_empty

From: Namhyung Kim
Date: Fri Jun 07 2024 - 16:30:32 EST


So that it can skip events with no sample according to the config value.
This can omit the dummy event in the output of perf report --group.

An example output:

$ sudo perf mem record -a sleep 1
$ sudo perf report --group

Before)
#
# Samples: 232 of events 'cpu/mem-loads,ldlat=30/P, cpu/mem-stores/P, dummy:u'
# Event count (approx.): 3089861
#
# Overhead Command Shared Object Symbol
# ........................ ........... ................. .....................................
#
9.29% 0.00% 0.00% swapper [kernel.kallsyms] [k] update_blocked_averages
5.26% 0.15% 0.00% swapper [kernel.kallsyms] [k] __update_load_avg_se
4.15% 0.00% 0.00% perf-exec [kernel.kallsyms] [k] slab_update_freelist.isra.0
3.87% 0.00% 0.00% perf-exec [kernel.kallsyms] [k] memcg_slab_post_alloc_hook
3.79% 0.17% 0.00% swapper [kernel.kallsyms] [k] enqueue_task_fair
3.63% 0.00% 0.00% sleep [kernel.kallsyms] [k] next_uptodate_page
2.86% 0.00% 0.00% swapper [kernel.kallsyms] [k] __update_load_avg_cfs_rq
2.78% 0.00% 0.00% swapper [kernel.kallsyms] [k] __schedule
2.34% 0.00% 0.00% swapper [kernel.kallsyms] [k] intel_idle
2.32% 0.97% 0.00% swapper [kernel.kallsyms] [k] psi_group_change

After)
#
# Samples: 232 of events 'cpu/mem-loads,ldlat=30/P, cpu/mem-stores/P'
# Event count (approx.): 3089861
#
# Overhead Command Shared Object Symbol
# ................ ........... ................. .....................................
#
9.29% 0.00% swapper [kernel.kallsyms] [k] update_blocked_averages
5.26% 0.15% swapper [kernel.kallsyms] [k] __update_load_avg_se
4.15% 0.00% perf-exec [kernel.kallsyms] [k] slab_update_freelist.isra.0
3.87% 0.00% perf-exec [kernel.kallsyms] [k] memcg_slab_post_alloc_hook
3.79% 0.17% swapper [kernel.kallsyms] [k] enqueue_task_fair
3.63% 0.00% sleep [kernel.kallsyms] [k] next_uptodate_page
2.86% 0.00% swapper [kernel.kallsyms] [k] __update_load_avg_cfs_rq
2.78% 0.00% swapper [kernel.kallsyms] [k] __schedule
2.34% 0.00% swapper [kernel.kallsyms] [k] intel_idle
2.32% 0.97% swapper [kernel.kallsyms] [k] psi_group_change

Now it doesn't have a column for the dummy event.

Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
tools/perf/ui/hist.c | 18 ++++++++++++++++--
tools/perf/util/evsel.c | 13 ++++++++++---
tools/perf/util/python.c | 3 +++
3 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/tools/perf/ui/hist.c b/tools/perf/ui/hist.c
index 7e863cd92781..5d1f04f66a5a 100644
--- a/tools/perf/ui/hist.c
+++ b/tools/perf/ui/hist.c
@@ -95,6 +95,10 @@ static int __hpp__fmt(struct perf_hpp *hpp, struct hist_entry *he,
}

for (i = 0; i < nr_members; i++) {
+ if (symbol_conf.skip_empty &&
+ values[i].hists->stats.nr_samples == 0)
+ continue;
+
ret += __hpp__fmt_print(hpp, values[i].hists, values[i].val,
values[i].samples, fmt, len,
print_fn, fmtype);
@@ -296,8 +300,18 @@ static int hpp__width_fn(struct perf_hpp_fmt *fmt,
int len = fmt->user_len ?: fmt->len;
struct evsel *evsel = hists_to_evsel(hists);

- if (symbol_conf.event_group)
- len = max(len, evsel->core.nr_members * fmt->len);
+ if (symbol_conf.event_group) {
+ int nr = 0;
+ struct evsel *pos;
+
+ for_each_group_evsel(pos, evsel) {
+ if (!symbol_conf.skip_empty ||
+ evsel__hists(pos)->stats.nr_samples)
+ nr++;
+ }
+
+ len = max(len, nr * fmt->len);
+ }

if (len < (int)strlen(fmt->name))
len = strlen(fmt->name);
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 4f818ab6b662..befb80c272d2 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -53,6 +53,7 @@
#include "../perf-sys.h"
#include "util/parse-branch-options.h"
#include "util/bpf-filter.h"
+#include "util/hist.h"
#include <internal/xyarray.h>
#include <internal/lib.h>
#include <internal/threadmap.h>
@@ -830,16 +831,22 @@ const char *evsel__group_name(struct evsel *evsel)
int evsel__group_desc(struct evsel *evsel, char *buf, size_t size)
{
int ret = 0;
+ bool first = true;
struct evsel *pos;
const char *group_name = evsel__group_name(evsel);

if (!evsel->forced_leader)
ret = scnprintf(buf, size, "%s { ", group_name);

- ret += scnprintf(buf + ret, size - ret, "%s", evsel__name(evsel));
+ for_each_group_evsel(pos, evsel) {
+ if (symbol_conf.skip_empty &&
+ evsel__hists(pos)->stats.nr_samples == 0)
+ continue;

- for_each_group_member(pos, evsel)
- ret += scnprintf(buf + ret, size - ret, ", %s", evsel__name(pos));
+ ret += scnprintf(buf + ret, size - ret, "%s%s",
+ first ? "" : ", ", evsel__name(pos));
+ first = false;
+ }

if (!evsel->forced_leader)
ret += scnprintf(buf + ret, size - ret, " }");
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index 0aeb97c11c03..88f98f2772fb 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -23,6 +23,7 @@
#include "util/env.h"
#include "util/pmu.h"
#include "util/pmus.h"
+#include "util/symbol_conf.h"
#include <internal/lib.h>
#include "util.h"

@@ -50,6 +51,8 @@
#define Py_TYPE(ob) (((PyObject*)(ob))->ob_type)
#endif

+struct symbol_conf symbol_conf;
+
/*
* Avoid bringing in event parsing.
*/
--
2.45.2.505.gda0bf45e8d-goog