lockstat: Filter for only Android monitor locks
Signed-off-by: Joel Fernandes <joel@joelfernandes.org>
diff --git a/bcc/misc/lockstat.py b/bcc/misc/lockstat.py
old mode 100755
new mode 100644
index fb1edbe..fa3edda
--- a/bcc/misc/lockstat.py
+++ b/bcc/misc/lockstat.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env bcc-py
+#!/usr/bin/python
#
# lockstat Trace and display lock contention stats
#
@@ -15,23 +15,24 @@
import subprocess
import os
+# One Lock object per TGID and uaddr.
class Lock(object):
def __init__(self):
self.contention_count = 0
self.elapsed_blocked = 0
self.thread_count = 0
+ self.last_stack_syms = []
- def update(self, count, block_time):
+ def update(self, count, block_time, last_stack_syms):
self.contention_count += count
self.elapsed_blocked += block_time
self.thread_count += 1
+ self.last_stack_syms = last_stack_syms
def run_command_get_pid(command):
p = subprocess.Popen(command.split())
return p.pid
-
-
examples = """
EXAMPLES:
@@ -103,15 +104,16 @@
struct lock_info_t {
u64 elapsed_blocked;
u64 contention_count;
+ u64 sid;
};
-
BPF_HASH(pid_lock, u32, u64);
BPF_HASH(pid_blocktime, u32, u64);
BPF_HASH(tgid_comm, u32, struct comm_t);
BPF_HASH(lock_stats, struct lock_key_t, struct lock_info_t, 1000000);
+BPF_STACK_TRACE(stack_traces, 16384);
-static inline int update_stats(u32 pid, u32 tgid, u64 uaddr, u64 block_time) {
+static inline int update_stats(u32 pid, u32 tgid, u64 uaddr, u64 block_time, u64 sid) {
struct lock_key_t key = {};
struct lock_info_t zero = {};
struct lock_info_t *info;
@@ -122,6 +124,7 @@
info = lock_stats.lookup_or_init(&key, &zero);
info->elapsed_blocked += block_time;
info->contention_count++;
+ info->sid = sid;
if (0 == tgid_comm.lookup(&tgid)) {
struct comm_t comm;
@@ -168,12 +171,15 @@
u64 *uaddr = pid_lock.lookup(&pid);
u64 timestamp = bpf_ktime_get_ns();
u64 elapsed;
+ u64 sid;
if (blocktime == 0 || uaddr == 0)
return 0; // not FUTEX_WAIT, or (less likely) missed futex_enter
elapsed = timestamp - *blocktime;
- update_stats(pid, tgid, *uaddr, elapsed);
+
+ sid = stack_traces.get_stackid(ctx, BPF_F_USER_STACK);
+ update_stats(pid, tgid, *uaddr, elapsed, sid);
pid_lock.delete(&pid);
pid_blocktime.delete(&pid);
@@ -202,19 +208,58 @@
bpf_program.attach_kprobe(event="SyS_futex", fn_name="sys_futex_enter")
bpf_program.attach_kretprobe(event="SyS_futex", fn_name="sys_futex_exit")
+def get_syms(stack, pid):
+ global bpf_program
+ syms = []
+ for addr in stack:
+ s = bpf_program.sym(addr, pid, show_offset=True)
+ syms.append(s)
+ return syms
+
+def print_syms(syms):
+ print("=========")
+ for f in syms:
+ print(f)
+ print("=========")
+
+def is_android_monitor_lock(syms):
+ for s in syms:
+ if 'art::Monitor::Lock' in s:
+ return True
+ return False
+
+def disp_stack(stack, pid):
+ for addr in stack:
+ s = bpf_program.sym(addr, pid, show_offset=True)
+
def create_tgid_stats():
+ global bpf_program
stats = bpf_program["lock_stats"]
res = {}
+ stack_traces = bpf_program['stack_traces']
for key, val in stats.items():
+ # Only display Android monitor locks
+ if val.sid >= 0:
+ ust = stack_traces.walk(val.sid)
+ syms = get_syms(ust, key.pid)
+ if not is_android_monitor_lock(syms):
+ continue
+ else:
+ continue
+
if not key.tgid in res:
res[key.tgid] = {}
if not key.uaddr in res[key.tgid]:
res[key.tgid][key.uaddr] = Lock()
+
lock = res[key.tgid][key.uaddr]
- lock.update(val.contention_count, val.elapsed_blocked)
+ lock.update(val.contention_count, val.elapsed_blocked, syms)
return res
def print_comm_stats(stats):
+ if stats == {}:
+ return
+
comms = bpf_program["tgid_comm"]
print("\n%s:" % (datetime.now().strftime("%H:%M:%S")))
for tgid, locks in stats.items():
@@ -229,6 +274,12 @@
stats.contention_count, stats.thread_count,
stats.elapsed_blocked / stats.contention_count / 1000))
+ # No use of displaying lock stacks since we're only
+ # filtering for Android monitor locks.
+ #
+ # print("Last stack for this lock:")
+ # print_syms(stats.last_stack_syms)
+
count_so_far = 0
while True:
if trace_all:
