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Message-ID: <20250129001905.619859-5-ctshao@google.com>
Date: Tue, 28 Jan 2025 16:15:00 -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, nathan@...nel.org,
ndesaulniers@...gle.com, morbo@...gle.com, justinstitt@...gle.com,
linux-perf-users@...r.kernel.org, bpf@...r.kernel.org, llvm@...ts.linux.dev
Subject: [PATCH v3 4/5] perf lock: Report owner stack in usermode
Parse `owner_lock_stat` into a rb tree, and report owner lock stats with
stack trace in order.
Example output:
$ sudo ~/linux/tools/perf/perf lock con -abvo -Y mutex-spin -E3 perf bench sched pipe
...
contended total wait max wait avg wait type caller
171 1.55 ms 20.26 us 9.06 us mutex pipe_read+0x57
0xffffffffac6318e7 pipe_read+0x57
0xffffffffac623862 vfs_read+0x332
0xffffffffac62434b ksys_read+0xbb
0xfffffffface604b2 do_syscall_64+0x82
0xffffffffad00012f entry_SYSCALL_64_after_hwframe+0x76
36 193.71 us 15.27 us 5.38 us mutex pipe_write+0x50
0xffffffffac631ee0 pipe_write+0x50
0xffffffffac6241db vfs_write+0x3bb
0xffffffffac6244ab ksys_write+0xbb
0xfffffffface604b2 do_syscall_64+0x82
0xffffffffad00012f entry_SYSCALL_64_after_hwframe+0x76
4 51.22 us 16.47 us 12.80 us mutex do_epoll_wait+0x24d
0xffffffffac691f0d do_epoll_wait+0x24d
0xffffffffac69249b do_epoll_pwait.part.0+0xb
0xffffffffac693ba5 __x64_sys_epoll_pwait+0x95
0xfffffffface604b2 do_syscall_64+0x82
0xffffffffad00012f entry_SYSCALL_64_after_hwframe+0x76
=== owner stack trace ===
3 31.24 us 15.27 us 10.41 us mutex pipe_read+0x348
0xffffffffac631bd8 pipe_read+0x348
0xffffffffac623862 vfs_read+0x332
0xffffffffac62434b ksys_read+0xbb
0xfffffffface604b2 do_syscall_64+0x82
0xffffffffad00012f entry_SYSCALL_64_after_hwframe+0x76
...
Signed-off-by: Chun-Tse Shao <ctshao@...gle.com>
---
tools/perf/builtin-lock.c | 20 ++++++++--
tools/perf/util/bpf_lock_contention.c | 54 +++++++++++++++++++++++++++
tools/perf/util/lock-contention.h | 7 ++++
3 files changed, 78 insertions(+), 3 deletions(-)
diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index 9bebc186286f..d9b0d7472aea 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -42,6 +42,7 @@
#include <linux/zalloc.h>
#include <linux/err.h>
#include <linux/stringify.h>
+#include <linux/rbtree.h>
static struct perf_session *session;
static struct target target;
@@ -1817,6 +1818,22 @@ static void print_contention_result(struct lock_contention *con)
break;
}
+ if (con->owner && con->save_callstack) {
+ struct rb_root root = RB_ROOT;
+
+ if (symbol_conf.field_sep)
+ fprintf(lock_output, "# owner stack trace:\n");
+ else
+ fprintf(lock_output, "\n=== owner stack trace ===\n\n");
+ while ((st = pop_owner_stack_trace(con)))
+ insert_to(&root, st, compare);
+
+ while ((st = pop_from(&root))) {
+ print_lock_stat(con, st);
+ zfree(st);
+ }
+ }
+
if (print_nr_entries) {
/* update the total/bad stats */
while ((st = pop_from_result())) {
@@ -1962,9 +1979,6 @@ static int check_lock_contention_options(const struct option *options,
}
}
- if (show_lock_owner)
- show_thread_stats = true;
-
return 0;
}
diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
index 795e2374facc..cf3267e46589 100644
--- a/tools/perf/util/bpf_lock_contention.c
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -549,6 +549,60 @@ static const char *lock_contention_get_name(struct lock_contention *con,
return name_buf;
}
+struct lock_stat *pop_owner_stack_trace(struct lock_contention *con)
+{
+ int stacks_fd, stat_fd;
+ u64 *stack_trace;
+ s32 stack_id;
+ struct contention_key ckey = {};
+ struct contention_data cdata = {};
+ size_t stack_size = con->max_stack * sizeof(*stack_trace);
+ struct lock_stat *st;
+ char name[KSYM_NAME_LEN];
+
+ stacks_fd = bpf_map__fd(skel->maps.owner_stacks);
+ stat_fd = bpf_map__fd(skel->maps.owner_stat);
+ if (!stacks_fd || !stat_fd)
+ return NULL;
+
+ stack_trace = zalloc(stack_size);
+ if (stack_trace == NULL)
+ return NULL;
+
+ if (bpf_map_get_next_key(stacks_fd, NULL, stack_trace))
+ return NULL;
+
+ bpf_map_lookup_elem(stacks_fd, stack_trace, &stack_id);
+ ckey.stack_id = stack_id;
+ bpf_map_lookup_elem(stat_fd, &ckey, &cdata);
+
+ st = zalloc(sizeof(struct lock_stat));
+ if (!st)
+ return NULL;
+
+ strcpy(name,
+ stack_trace[0] ? lock_contention_get_name(con, NULL, stack_trace, 0) : "unknown");
+
+ st->name = strdup(name);
+ if (!st->name)
+ return NULL;
+
+ st->flags = cdata.flags;
+ st->nr_contended = cdata.count;
+ st->wait_time_total = cdata.total_time;
+ st->wait_time_max = cdata.max_time;
+ st->wait_time_min = cdata.min_time;
+ st->callstack = stack_trace;
+
+ if (cdata.count)
+ st->avg_wait_time = cdata.total_time / cdata.count;
+
+ bpf_map_delete_elem(stacks_fd, stack_trace);
+ bpf_map_delete_elem(stat_fd, &ckey);
+
+ return st;
+}
+
int lock_contention_read(struct lock_contention *con)
{
int fd, stack, err = 0;
diff --git a/tools/perf/util/lock-contention.h b/tools/perf/util/lock-contention.h
index a09f7fe877df..97fd33c57f17 100644
--- a/tools/perf/util/lock-contention.h
+++ b/tools/perf/util/lock-contention.h
@@ -168,6 +168,8 @@ int lock_contention_stop(void);
int lock_contention_read(struct lock_contention *con);
int lock_contention_finish(struct lock_contention *con);
+struct lock_stat *pop_owner_stack_trace(struct lock_contention *con);
+
#else /* !HAVE_BPF_SKEL */
static inline int lock_contention_prepare(struct lock_contention *con __maybe_unused)
@@ -187,6 +189,11 @@ static inline int lock_contention_read(struct lock_contention *con __maybe_unuse
return 0;
}
+struct lock_stat *pop_owner_stack_trace(struct lock_contention *con)
+{
+ return NULL;
+}
+
#endif /* HAVE_BPF_SKEL */
#endif /* PERF_LOCK_CONTENTION_H */
--
2.48.1.262.g85cc9f2d1e-goog
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