Added pid filter and minor fixes

tools/lockstat.py

@@ -26,6 +26,11 @@ def update(self, count, block_time):
  self.elapsed_blocked += block_time
  self.thread_count += 1
 
+def run_command_get_pid(command):
+ p = subprocess.Popen(command.split())
+ return p.pid
+
+
 
 examples = """
 EXAMPLES:
@@ -38,7 +43,7 @@ def update(self, count, block_time):
  every 5 seconds
 ./lockstat -p <pid> -t
  Trace for a specified pid and print a message on each entry and exit to
- sys_futex
+ sys_futex until interrupted or killed
 ./lockstat -p <pid> 10
  Trace the specified pid and show a message every 10 seconds
 ./lockstat -c <command> 1 30
@@ -106,13 +111,11 @@ def update(self, count, block_time):
 BPF_HASH(tgid_comm, u32, struct comm_t);
 BPF_HASH(lock_stats, struct lock_key_t, struct lock_info_t, 1000000);
 
-static inline int update_stats(u64 pid_tgid, u64 uaddr, u64 block_time) {
+static inline int update_stats(u32 pid, u32 tgid, u64 uaddr, u64 block_time) {
  struct lock_key_t key = {};
  struct lock_info_t zero = {};
  struct lock_info_t *info;
 
- u32 pid = pid_tgid;
- u32 tgid = (pid_tgid >> 32);
  key.pid = pid;
  key.tgid = tgid;
  key.uaddr = uaddr;
@@ -136,21 +139,31 @@ def update(self, count, block_time):
  if (cmd != FUTEX_WAIT)
  return 0;
 
- u32 pid = bpf_get_current_pid_tgid();
+ u64 pid_tgid = bpf_get_current_pid_tgid();
+ u32 pid = pid_tgid;
+ u32 tgid = pid_tgid >> 32;
+
+ if (!(THREAD_FILTER))
+ return 0;
+
  u64 timestamp = bpf_ktime_get_ns();
  u64 uaddr64 = (u64) uaddr;
  pid_lock.update(&pid, &uaddr64);
  pid_blocktime.update(&pid, &timestamp);
 
  if (SHOULD_PRINT)
- bpf_trace_printk("enter sys_futex, pid = %u, uaddr = %u, "
+ bpf_trace_printk("enter sys_futex, pid = %u, uaddr = %x, "
  "cmd = %u\\n", pid, uaddr64, cmd);
  return 0;
 }
 
 int sys_futex_exit(struct pt_regs *ctx) {
  u64 pid_tgid = bpf_get_current_pid_tgid();
  u32 pid = pid_tgid;
+ u32 tgid = pid_tgid >> 32;
+ if (!(THREAD_FILTER))
+ return 0;
+
  u64 *blocktime = pid_blocktime.lookup(&pid);
  u64 *uaddr = pid_lock.lookup(&pid);
  u64 timestamp = bpf_ktime_get_ns();
@@ -160,12 +173,12 @@ def update(self, count, block_time):
  return 0; // not FUTEX_WAIT, or (less likely) missed futex_enter
 
  elapsed = timestamp - *blocktime;
- update_stats(pid_tgid, *uaddr, elapsed);
+ update_stats(pid, tgid, *uaddr, elapsed);
  pid_lock.delete(&pid);
  pid_blocktime.delete(&pid);
 
  if (SHOULD_PRINT) {
- bpf_trace_printk("exit sys_futex, uaddr = %u, elapsed = %uns\\n",
+ bpf_trace_printk("exit sys_futex, uaddr = %x, elapsed = %uns\\n",
  uaddr == 0 ? 0 : *uaddr, elapsed);
  }
  return 0;
@@ -175,12 +188,19 @@ def update(self, count, block_time):
 
 bpf_source = bpf_source.replace("SHOULD_PRINT", "1" if trace_all else "0")
 
-bpf_program = BPF(text=bpf_source)
+thread_filter = '1'
+if pid != -1:
+ print("Tracing pid %d, Ctrl+C to quit." % pid)
+ # 'tgid' in kernel space is what people thin of as 'pid' in userspace
+ thread_filter = "tgid == %d" % pid
+else:
+ print("Tracing all processes, Ctrl+C to quit.")
 
-print("Attaching to pid %d, Ctrl+C to quit." % pid)
+bpf_source = bpf_source.replace("THREAD_FILTER", thread_filter)
 
-bpf_program.attach_kprobe(event="SyS_futex", fn_name="sys_futex_enter", pid=pid)
-bpf_program.attach_kretprobe(event="SyS_futex", fn_name="sys_futex_exit", pid=pid)
+bpf_program = BPF(text=bpf_source)
+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 create_tgid_stats():
  stats = bpf_program["lock_stats"]
@@ -204,9 +224,10 @@ def print_comm_stats(stats):
  key=lambda x: x[1].elapsed_blocked,
  reverse=True)
  for addr, stats in sorted_locks:
- print(" %x: %dms (%d contentions affected %d threads)" %
+ print(" %x: %dms (%d contentions involving %d threads, avg %dus)" %
  (addr, stats.elapsed_blocked / 1000000,
- stats.contention_count, stats.thread_count))
+ stats.contention_count, stats.thread_count,
+ stats.elapsed_blocked / stats.contention_count / 1000))
 
 count_so_far = 0
 while True: