linux-kernel - [PATCH 2/3] perf lock: Add -m/--map-length option

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Date:   Tue,  2 Aug 2022 00:35:10 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        linux-perf-users@...r.kernel.org, Will Deacon <will@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Song Liu <songliubraving@...com>,
        Blake Jones <blakejones@...gle.com>
Subject: [PATCH 2/3] perf lock: Add -m/--map-length option

The -m/--map-length option is to control number of max entries in the
perf lock contention BPF maps.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/Documentation/perf-lock.txt |  4 ++++
 tools/perf/builtin-lock.c              | 23 ++++++++++++++++++++++-
 tools/perf/util/bpf_lock_contention.c  |  3 +++
 tools/perf/util/lock-contention.h      |  1 +
 4 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Documentation/perf-lock.txt b/tools/perf/Documentation/perf-lock.txt
index 7949d2e6891b..2101644785e0 100644
--- a/tools/perf/Documentation/perf-lock.txt
+++ b/tools/perf/Documentation/perf-lock.txt
@@ -145,6 +145,10 @@ CONTENTION OPTIONS
 --tid=::
         Record events on existing thread ID (comma separated list).
 
+-m::
+--map-length::
+	Maximum number of BPF map entries (default: 10240).
+
 
 SEE ALSO
 --------
diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index eef778b7d33d..e32fdcd497e0 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -55,6 +55,7 @@ static struct rb_root		thread_stats;
 static bool combine_locks;
 static bool show_thread_stats;
 static bool use_bpf;
+static unsigned long bpf_map_len = 10240;
 
 static enum {
 	LOCK_AGGR_ADDR,
@@ -1597,6 +1598,7 @@ static int __cmd_contention(int argc, const char **argv)
 	struct lock_contention con = {
 		.target = &target,
 		.result = &lockhash_table[0],
+		.map_len = bpf_map_len,
 	};
 
 	session = perf_session__new(use_bpf ? NULL : &data, &eops);
@@ -1786,6 +1788,24 @@ static int __cmd_record(int argc, const char **argv)
 	return ret;
 }
 
+static int parse_map_length(const struct option *opt, const char *str,
+			    int unset __maybe_unused)
+{
+	unsigned long *len = (unsigned long *)opt->value;
+	unsigned long val;
+	char *endptr;
+
+	errno = 0;
+	val = strtoul(str, &endptr, 0);
+	if (*endptr != '\0' || errno != 0) {
+		pr_err("invalid BPF map length: %s\n", str);
+		return -1;
+	}
+
+	*len = val;
+	return 0;
+}
+
 int cmd_lock(int argc, const char **argv)
 {
 	const struct option lock_options[] = {
@@ -1835,9 +1855,10 @@ int cmd_lock(int argc, const char **argv)
 		    "List of cpus to monitor"),
 	OPT_STRING('p', "pid", &target.pid, "pid",
 		   "Trace on existing process id"),
-	/* TODO: Add short option -t after -t/--tracer can be removed. */
 	OPT_STRING(0, "tid", &target.tid, "tid",
 		   "Trace on existing thread id (exclusive to --pid)"),
+	OPT_CALLBACK('m', "map-length", &bpf_map_len, "len",
+		     "Max number of BPF map entries", parse_map_length),
 	OPT_PARENT(lock_options)
 	};
 
diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
index f5e2b4f19a72..26128e5bb659 100644
--- a/tools/perf/util/bpf_lock_contention.c
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -40,6 +40,9 @@ int lock_contention_prepare(struct lock_contention *con)
 		return -1;
 	}
 
+	bpf_map__set_max_entries(skel->maps.stacks, con->map_len);
+	bpf_map__set_max_entries(skel->maps.lock_stat, con->map_len);
+
 	if (target__has_cpu(target))
 		ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
 	if (target__has_task(target))
diff --git a/tools/perf/util/lock-contention.h b/tools/perf/util/lock-contention.h
index a0df5308cca4..b09fd6eb978a 100644
--- a/tools/perf/util/lock-contention.h
+++ b/tools/perf/util/lock-contention.h
@@ -112,6 +112,7 @@ struct lock_contention {
 	struct target *target;
 	struct machine *machine;
 	struct hlist_head *result;
+	unsigned long map_len;
 };
 
 #ifdef HAVE_BPF_SKEL
-- 
2.37.1.455.g008518b4e5-goog