linux-kernel - [PATCH v1 1/4] perf lock: Add bpf maps for owner stack tracing

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Message-ID: <20250110051346.1507178-2-ctshao@google.com>
Date: Thu,  9 Jan 2025 21:11:41 -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 v1 1/4] perf lock: Add bpf maps for owner stack tracing

Add few bpf maps in order to tracing owner stack.

Signed-off-by: Chun-Tse Shao <ctshao@...gle.com>
---
 tools/perf/util/bpf_lock_contention.c         | 17 ++++++--
 .../perf/util/bpf_skel/lock_contention.bpf.c  | 40 +++++++++++++++++--
 tools/perf/util/bpf_skel/lock_data.h          |  6 +++
 3 files changed, 56 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
index 41a1ad087895..c9c58f243ceb 100644
--- a/tools/perf/util/bpf_lock_contention.c
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -41,9 +41,20 @@ int lock_contention_prepare(struct lock_contention *con)
 	else
 		bpf_map__set_max_entries(skel->maps.task_data, 1);
 
-	if (con->save_callstack)
-		bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries);
-	else
+	if (con->save_callstack) {
+		bpf_map__set_max_entries(skel->maps.stacks,
+					 con->map_nr_entries);
+		if (con->owner) {
+			bpf_map__set_value_size(skel->maps.owner_stacks_entries,
+						con->max_stack * sizeof(u64));
+			bpf_map__set_value_size(
+				skel->maps.contention_owner_stacks,
+				con->max_stack * sizeof(u64));
+			bpf_map__set_key_size(skel->maps.owner_lock_stat,
+						con->max_stack * sizeof(u64));
+			skel->rodata->max_stack = con->max_stack;
+		}
+	} else
 		bpf_map__set_max_entries(skel->maps.stacks, 1);
 
 	if (target__has_cpu(target)) {
diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index 1069bda5d733..05da19fdab23 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -19,13 +19,37 @@
 #define LCB_F_PERCPU	(1U << 4)
 #define LCB_F_MUTEX	(1U << 5)
 
-/* callstack storage  */
+ /* tmp buffer for owner callstack */
 struct {
-	__uint(type, BPF_MAP_TYPE_STACK_TRACE);
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
 	__uint(key_size, sizeof(__u32));
 	__uint(value_size, sizeof(__u64));
+	__uint(max_entries, 1);
+} owner_stacks_entries SEC(".maps");
+
+/* a map for tracing lock address to owner data */
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u64)); // lock address
+	__uint(value_size, sizeof(cotd));
 	__uint(max_entries, MAX_ENTRIES);
-} stacks SEC(".maps");
+} contention_owner_tracing SEC(".maps");
+
+/* a map for tracing lock address to owner stacktrace */
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u64)); // lock address
+	__uint(value_size, sizeof(__u64)); // straktrace
+	__uint(max_entries, MAX_ENTRIES);
+} contention_owner_stacks SEC(".maps");
+
+/* owner callstack to contention data storage */
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u64));
+	__uint(value_size, sizeof(struct contention_data));
+	__uint(max_entries, MAX_ENTRIES);
+} owner_lock_stat SEC(".maps");
 
 /* maintain timestamp at the beginning of contention */
 struct {
@@ -43,6 +67,14 @@ struct {
 	__uint(max_entries, 1);
 } tstamp_cpu SEC(".maps");
 
+/* callstack storage  */
+struct {
+	__uint(type, BPF_MAP_TYPE_STACK_TRACE);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(__u64));
+	__uint(max_entries, MAX_ENTRIES);
+} stacks SEC(".maps");
+
 /* actual lock contention statistics */
 struct {
 	__uint(type, BPF_MAP_TYPE_HASH);
@@ -126,6 +158,7 @@ const volatile int needs_callstack;
 const volatile int stack_skip;
 const volatile int lock_owner;
 const volatile int use_cgroup_v2;
+const volatile int max_stack;
 
 /* determine the key of lock stat */
 const volatile int aggr_mode;
@@ -436,7 +469,6 @@ int contention_end(u64 *ctx)
 			return 0;
 		need_delete = true;
 	}
-
 	duration = bpf_ktime_get_ns() - pelem->timestamp;
 	if ((__s64)duration < 0) {
 		__sync_fetch_and_add(&time_fail, 1);
diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
index de12892f992f..1ef0bca9860e 100644
--- a/tools/perf/util/bpf_skel/lock_data.h
+++ b/tools/perf/util/bpf_skel/lock_data.h
@@ -3,6 +3,12 @@
 #ifndef UTIL_BPF_SKEL_LOCK_DATA_H
 #define UTIL_BPF_SKEL_LOCK_DATA_H
 
+typedef struct contention_owner_tracing_data {
+	u32 pid; // Who has the lock.
+	u64 timestamp; // The time while the owner acquires lock and contention is going on.
+	u32 count; // How many waiters for this lock.
+} cotd;
+
 struct tstamp_data {
 	u64 timestamp;
 	u64 lock;
-- 
2.47.1.688.g23fc6f90ad-goog