Make number of stack traces configurable from command line in example… (

iovisor#2500)

Make number of stack traces configurable from command line in examples/tracing/mallocstacks.py

examples/tracing/mallocstacks.py

@@ -17,16 +17,26 @@
 import sys
 
 if len(sys.argv) < 2:
- print("USAGE: mallocstacks PID")
+ print("USAGE: mallocstacks PID [NUM_STACKS=1024]")
  exit()
 pid = int(sys.argv[1])
+if len(sys.argv) == 3:
+ try:
+ assert int(sys.argv[2]) > 0, ""
+ except (ValueError, AssertionError) as e:
+ print("USAGE: mallocstacks PID [NUM_STACKS=1024]")
+ print("NUM_STACKS must be a non-zero, positive integer")
+ exit()
+ stacks = sys.argv[2]
+else:
+ stacks = "1024"
 
 # load BPF program
 b = BPF(text="""
 #include <uapi/linux/ptrace.h>
 
 BPF_HASH(calls, int);
-BPF_STACK_TRACE(stack_traces, 1024);
+BPF_STACK_TRACE(stack_traces, """ + stacks + """);
 
 int alloc_enter(struct pt_regs *ctx, size_t size) {
  int key = stack_traces.get_stackid(ctx,