linux-kernel - [PATCH v4 5/5] perf lock: Update documentation for -o option in contention mode

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Message-ID: <20250130052510.860318-6-ctshao@google.com>
Date: Wed, 29 Jan 2025 21:21:39 -0800
From: Chun-Tse Shao <ctshao@...gle.com>
To: linux-kernel@...r.kernel.org
Cc: Chun-Tse Shao <ctshao@...gle.com>, peterz@...radead.org, mingo@...hat.com, 
	acme@...nel.org, namhyung@...nel.org, mark.rutland@....com, 
	alexander.shishkin@...ux.intel.com, jolsa@...nel.org, irogers@...gle.com, 
	adrian.hunter@...el.com, kan.liang@...ux.intel.com, 
	linux-perf-users@...r.kernel.org, bpf@...r.kernel.org
Subject: [PATCH v4 5/5] perf lock: Update documentation for -o option in
 contention mode

This patch also decouple -o with -t, and shows warning to notify the new
behavior for -ov.

Signed-off-by: Chun-Tse Shao <ctshao@...gle.com>
---
 tools/perf/builtin-lock.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index 3dc100cf30ef..e16bda6ce525 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -1817,7 +1817,7 @@ static void print_contention_result(struct lock_contention *con)
 			break;
 	}
 
-	if (con->owner && con->save_callstack) {
+	if (con->owner && con->save_callstack && verbose > 0) {
 		struct rb_root root = RB_ROOT;
 
 		if (symbol_conf.field_sep)
@@ -1978,6 +1978,11 @@ static int check_lock_contention_options(const struct option *options,
 		}
 	}
 
+	if (show_lock_owner && !show_thread_stats) {
+		pr_warning("Now -o try to show owner's callstack instead of pid and comm.\n");
+		pr_warning("Please use -t option too to keep the old behavior.\n");
+	}
+
 	return 0;
 }
 
@@ -2569,7 +2574,8 @@ int cmd_lock(int argc, const char **argv)
 		     "Filter specific address/symbol of locks", parse_lock_addr),
 	OPT_CALLBACK('S', "callstack-filter", NULL, "NAMES",
 		     "Filter specific function in the callstack", parse_call_stack),
-	OPT_BOOLEAN('o', "lock-owner", &show_lock_owner, "show lock owners instead of waiters"),
+	OPT_BOOLEAN('o', "lock-owner", &show_lock_owner, "show lock owners instead of waiters.\n"
+		"\t\t\tThis option can be combined with -t, which shows owner's per thread lock stats, or -v, which shows owner's stacktrace"),
 	OPT_STRING_NOEMPTY('x', "field-separator", &symbol_conf.field_sep, "separator",
 		   "print result in CSV format with custom separator"),
 	OPT_BOOLEAN(0, "lock-cgroup", &show_lock_cgroups, "show lock stats by cgroup"),
-- 
2.48.1.362.g079036d154-goog