tools/deadlock: support specifies maxnum of threads and edge cases (i…

…ovisor#3455)

support to specify maxinum of threads and edge cases. The default values make map taking more than 0.5G memory which cause out-of-memory issue on some systems.
also fix an issue with python `open` so the open file is automatically closed upon file reading is done.

man/man8/deadlock.8

@@ -58,6 +58,14 @@ These symbols cannot be inlined in the binary.
 Comma-separated list of unlock symbols to trace. Default is
 pthread_mutex_unlock. These symbols cannot be inlined in the binary.
 .TP
+\-t THREADS, --threads THREADS
+Specifies the maximum number of threads to trace. default 65536.
+Note. 40 bytes per thread.
+.TP
+\-e EDGES, --edges EDGES
+Specifies the maximum number of edge cases that can be
+recorded. default 65536. Note. 88 bytes per edge case.
+.TP
 pid
 Pid to trace
 .SH EXAMPLES

tools/deadlock.c

@@ -30,7 +30,7 @@ struct thread_to_held_mutex_leaf_t {
 };
 
 // Map of thread ID -> array of (mutex addresses, stack id)
-BPF_HASH(thread_to_held_mutexes, u32, struct thread_to_held_mutex_leaf_t, 2097152);
+BPF_HASH(thread_to_held_mutexes, u32, struct thread_to_held_mutex_leaf_t, MAX_THREADS);
 
 // Key type for edges. Represents an edge from mutex1 => mutex2.
 struct edges_key_t {
@@ -47,7 +47,7 @@ struct edges_leaf_t {
 };
 
 // Represents all edges currently in the mutex wait graph.
-BPF_HASH(edges, struct edges_key_t, struct edges_leaf_t, 2097152);
+BPF_HASH(edges, struct edges_key_t, struct edges_leaf_t, MAX_EDGES);
 
 // Info about parent thread when a child thread is created.
 struct thread_created_leaf_t {

tools/deadlock.py

@@ -457,6 +457,16 @@ def main():
  help='Comma-separated list of unlock symbols to trace. Default is '
  'pthread_mutex_unlock. These symbols cannot be inlined in the binary.',
  )
+ parser.add_argument(
+ '-t', '--threads', type=int, default=65536,
+ help='Specifies the maximum number of threads to trace. default 65536. '
+ 'Note. 40 bytes per thread.'
+ )
+ parser.add_argument(
+ '-e', '--edges', type=int, default=65536,
+ help='Specifies the maximum number of edge cases that can be recorded. '
+ 'default 65536. Note. 88 bytes per edge case.'
+ )
  args = parser.parse_args()
  if not args.binary:
  try:
@@ -465,7 +475,11 @@ def main():
  print('%s. Is the process (pid=%d) running?' % (str(e), args.pid))
  sys.exit(1)
 
- bpf = BPF(src_file=b'deadlock.c')
+ with open('deadlock.c') as f:
+ text = f.read()
+ text = text.replace(b'MAX_THREADS', str(args.threads));
+ text = text.replace(b'MAX_EDGES', str(args.edges));
+ bpf = BPF(text=text)
 
  # Trace where threads are created
  bpf.attach_kretprobe(event=bpf.get_syscall_fnname('clone'), fn_name='trace_clone')

tools/deadlock_example.txt

@@ -340,6 +340,12 @@ optional arguments:
  Comma-separated list of unlock symbols to trace.
  Default is pthread_mutex_unlock. These symbols cannot
  be inlined in the binary.
+ -t THREADS, --threads THREADS
+ Specifies the maximum number of threads to trace.
+ default 65536. Note. 40 bytes per thread.
+ -e EDGES, --edges EDGES
+ Specifies the maximum number of edge cases that can be
+ recorded. default 65536. Note. 88 bytes per edge case.
 
 Examples:
  deadlock 181 # Analyze PID 181