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* [PATCH] tools: perf: add comm_ignore_digit column
@ 2026-03-05 18:18 Stephen Brennan
  2026-03-16 17:48 ` Namhyung Kim
  0 siblings, 1 reply; 3+ messages in thread
From: Stephen Brennan @ 2026-03-05 18:18 UTC (permalink / raw)
  To: Arnaldo Carvalho de Melo, Ingo Molnar, Peter Zijlstra,
	Namhyung Kim
  Cc: Mark Rutland, Adrian Hunter, Jiri Olsa, linux-perf-users,
	linux-kernel, Wangyang Guo, Dapeng Mi, Tianyou Li,
	Alexander Shishkin, James Clark, Stephen Brennan, Ian Rogers

The "comm" column allows grouping events by the process command. It is
intended to group like programs, despite having different PIDs. But some
workloads may adjust their own command, so that a unique identifier
(e.g. a PID or some other numeric value) is part of the command name.
This destroys the utility of "comm", forcing perf to place each unique
process name into its own bucket, which can contribute to a
combinatorial explosion of memory use in perf report.

Create a less strict version of this column, which ignores digits when
comparing command names. This allows "similar looking" processes to
again be placed in the same bucket.

Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
---
 tools/perf/util/hist.c |  1 +
 tools/perf/util/hist.h |  1 +
 tools/perf/util/sort.c | 92 +++++++++++++++++++++++++++++++++++++++++-
 tools/perf/util/sort.h |  1 +
 4 files changed, 94 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index ef4b569f7df46..6759826be8344 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -110,6 +110,7 @@ void hists__calc_col_len(struct hists *hists, struct hist_entry *h)
 	len = thread__comm_len(h->thread);
 	if (hists__new_col_len(hists, HISTC_COMM, len))
 		hists__set_col_len(hists, HISTC_THREAD, len + 8);
+	hists__new_col_len(hists, HISTC_COMM_IGNORE_DIGIT, len);
 
 	if (h->ms.map) {
 		len = dso__name_len(map__dso(h->ms.map));
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index 1d5ea632ca4e1..ae7e98bd9e46d 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -44,6 +44,7 @@ enum hist_column {
 	HISTC_THREAD,
 	HISTC_TGID,
 	HISTC_COMM,
+	HISTC_COMM_IGNORE_DIGIT,
 	HISTC_CGROUP_ID,
 	HISTC_CGROUP,
 	HISTC_PARENT,
diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
index f3a565b0e2307..e6012b2457c5d 100644
--- a/tools/perf/util/sort.c
+++ b/tools/perf/util/sort.c
@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
+#include <ctype.h>
 #include <errno.h>
 #include <inttypes.h>
 #include <regex.h>
@@ -265,6 +266,93 @@ struct sort_entry sort_comm = {
 	.se_width_idx	= HISTC_COMM,
 };
 
+/* --sort comm_ignore_digit */
+
+static int64_t strcmp_nodigit(const char *left, const char *right)
+{
+	for (;;) {
+		while (*left && isdigit(*left))
+			left++;
+		while (*right && isdigit(*right))
+			right++;
+		if (*left == *right && !*left) {
+			return 0;
+		} else if (*left == *right) {
+			left++;
+			right++;
+		} else {
+			return (int64_t)*left - (int64_t)*right;
+		}
+	}
+}
+
+static int64_t
+sort__comm_ignore_digit_cmp(struct hist_entry *left, struct hist_entry *right)
+{
+	return strcmp_nodigit(comm__str(right->comm), comm__str(left->comm));
+}
+
+static int64_t
+sort__comm_ignore_digit_collapse(struct hist_entry *left, struct hist_entry *right)
+{
+	return strcmp_nodigit(comm__str(right->comm), comm__str(left->comm));
+}
+
+static int64_t
+sort__comm_ignore_digit_sort(struct hist_entry *left, struct hist_entry *right)
+{
+	return strcmp_nodigit(comm__str(right->comm), comm__str(left->comm));
+}
+
+static int hist_entry__comm_ignore_digit_snprintf(struct hist_entry *he, char *bf,
+						size_t size, unsigned int width)
+{
+	int ret = 0;
+	unsigned int print_len, printed = 0, start = 0, end = 0;
+	bool in_digit;
+	const char *comm = comm__str(he->comm), *print;
+
+	while (printed < width && printed < size && comm[start]) {
+		in_digit = !!isdigit(comm[start]);
+		end = start + 1;
+		while (comm[end] && !!isdigit(comm[end]) == in_digit)
+			end++;
+		if (in_digit) {
+			print_len = 3; /* <N> */
+			print = "<N>";
+		} else {
+			print_len = end - start;
+			print = &comm[start];
+		}
+		print_len = min(print_len, width - printed);
+		ret = repsep_snprintf(bf + printed, size - printed, "%-.*s",
+					print_len, print);
+		if (ret < 0)
+			return ret;
+		start = end;
+		printed += ret;
+	}
+	/* Pad to width if necessary */
+	if (printed < width && printed < size) {
+		ret = repsep_snprintf(bf + printed, size - printed, "%-*.*s",
+				       width - printed, width - printed, "");
+		if (ret < 0)
+			return ret;
+		printed += ret;
+	}
+	return printed;
+}
+
+struct sort_entry sort_comm_ignore_digit = {
+	.se_header	= "CommandIgnoreDigit",
+	.se_cmp		= sort__comm_ignore_digit_cmp,
+	.se_collapse	= sort__comm_ignore_digit_collapse,
+	.se_sort	= sort__comm_ignore_digit_sort,
+	.se_snprintf	= hist_entry__comm_ignore_digit_snprintf,
+	.se_filter	= hist_entry__thread_filter,
+	.se_width_idx	= HISTC_COMM_IGNORE_DIGIT,
+};
+
 /* --sort dso */
 
 static int64_t _sort__dso_cmp(struct map *map_l, struct map *map_r)
@@ -2576,6 +2664,7 @@ static struct sort_dimension common_sort_dimensions[] = {
 	DIM(SORT_PID, "pid", sort_thread),
 	DIM(SORT_TGID, "tgid", sort_tgid),
 	DIM(SORT_COMM, "comm", sort_comm),
+	DIM(SORT_COMM_IGNORE_DIGIT, "comm_ignore_digit", sort_comm_ignore_digit),
 	DIM(SORT_DSO, "dso", sort_dso),
 	DIM(SORT_SYM, "symbol", sort_sym),
 	DIM(SORT_PARENT, "parent", sort_parent),
@@ -3675,7 +3764,7 @@ int sort_dimension__add(struct perf_hpp_list *list, const char *tok,
 			list->socket = 1;
 		} else if (sd->entry == &sort_thread) {
 			list->thread = 1;
-		} else if (sd->entry == &sort_comm) {
+		} else if (sd->entry == &sort_comm || sd->entry == &sort_comm_ignore_digit) {
 			list->comm = 1;
 		} else if (sd->entry == &sort_type_offset) {
 			symbol_conf.annotate_data_member = true;
@@ -4022,6 +4111,7 @@ static bool get_elide(int idx, FILE *output)
 	case HISTC_DSO:
 		return __get_elide(symbol_conf.dso_list, "dso", output);
 	case HISTC_COMM:
+	case HISTC_COMM_IGNORE_DIGIT:
 		return __get_elide(symbol_conf.comm_list, "comm", output);
 	default:
 		break;
diff --git a/tools/perf/util/sort.h b/tools/perf/util/sort.h
index d7787958e06b9..6819934b4d48a 100644
--- a/tools/perf/util/sort.h
+++ b/tools/perf/util/sort.h
@@ -43,6 +43,7 @@ enum sort_type {
 	/* common sort keys */
 	SORT_PID,
 	SORT_COMM,
+	SORT_COMM_IGNORE_DIGIT,
 	SORT_DSO,
 	SORT_SYM,
 	SORT_PARENT,
-- 
2.47.3


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2026-03-05 18:18 [PATCH] tools: perf: add comm_ignore_digit column Stephen Brennan
2026-03-16 17:48 ` Namhyung Kim
2026-03-16 17:59   ` Stephen Brennan

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