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Filename : glibc-malloc.stp
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#!/usr/bin/stap

# http://developerblog.redhat.com/2015/01/06/malloc-systemtap-probes-an-example/


global sbrk, waits, arenalist, mmap_threshold = 131072, heaplist
  
  
# sbrk accounting
  
probe process("/lib*/libc.so.6").mark("memory_sbrk_more")
{
  sbrk += $arg2
}
  
probe process("/lib*/libc.so.6").mark("memory_sbrk_less")
{
  sbrk -= $arg2
}


# threshold tracking

probe process("/lib*/libc.so.6").mark("memory_mallopt_free_dyn_thresholds")
{
  printf("%d: New thresholds: mmap: %ld bytes, trim: %ld bytes\n", tid(), $arg1,
         $arg2)
  mmap_threshold = $arg1
}


# arena accounting

probe process("/lib*/libc.so.6").mark("memory_arena_new")
{
  printf ("%d: Created new arena\n", tid())
  arenalist[$arg1, tid()] = 1
}

probe process("/usr/lib*/libc.so.6").mark("memory_arena_reuse_wait")
{
  waits[tid()]++
}

probe process("/usr/lib*/libc.so.6").mark("memory_arena_reuse")
{
  if ($arg2 != 0)
    {
      printf ("%d: failed to allocate on own arena, trying another\n", tid())
      arenalist[$arg1, tid()] = 1
    }
}

probe process("/usr/lib*/libc.so.6").mark("memory_arena_reuse_free_list")
{
  arenalist[$arg1, tid()] = 1
}

probe process.thread.end
{
  /* Find the thread and mark its arena as unused.  */
  %( systemtap_v >= "2.6"
  %?
    delete arenalist[*, tid()]
  %:
    foreach ([a, t] in arenalist)
      if (t == tid())
        break
    delete arenalist[a, t]
  %)
}


# heap accounting

probe process("/usr/lib*/libc.so.6").mark("memory_heap_new")
{
  printf("%d: New heap\n", tid());
  heaplist[$arg1] = $arg2
}

probe process("/usr/lib*/libc.so.6").mark("memory_heap_more")
{
  heaplist[$arg1] = $arg2
}

probe process("/usr/lib*/libc.so.6").mark("memory_heap_less")
{
  heaplist[$arg1] = $arg2
}

probe process("/usr/lib*/libc.so.6").mark("memory_heap_free")
{
  delete heaplist[$arg1]
}


# reporting

probe begin
{
  if (target() == 0) error ("please specify target process with -c / -x")
}

probe end
{
  printf ("malloc information for pid %d\n", target())
  printf ("Contention: \n")
  foreach (t in waits)
  printf ("\t%d: %d waits\n", t, waits[t])
  
  print("Active arenas:\n")
  foreach ([a, t] in arenalist)
  {
    if (arenalist[a, t])
      printf ("\t%d -> %p\n", t, a)
  }
  
  print ("Allocated heaps:\n")
  foreach (h in heaplist)
  {
    if (heaplist[h])
      printf ("\t%p -> %ld bytes\n", h, heaplist[h])
  }
  
  printf ("Total sbrk: %ld bytes\n", sbrk)
  printf ("Mmap threshold in the end: %ld kb\n", mmap_threshold / 1024)
}