Merge pull request iovisor#417 from iovisor/funccount_alternate

Remove use of update() in funccount

src/python/bcc/__init__.py

@@ -33,8 +33,8 @@
 tracefile = None
 TRACEFS = "/sys/kernel/debug/tracing"
 KALLSYMS = "/proc/kallsyms"
-ksym_addrs = []
-ksym_names = []
+ksyms = []
+ksym_names = {}
 ksym_loaded = 0
 _kprobe_limit = 1000
 
@@ -642,7 +642,7 @@ def trace_print(self, fmt=None):
 
  @staticmethod
  def _load_kallsyms():
- global ksym_loaded, ksym_addrs, ksym_names
+ global ksym_loaded, ksyms, ksym_names
  if ksym_loaded:
  return
  try:
@@ -654,19 +654,20 @@ def _load_kallsyms():
  cols = line.split()
  name = cols[2]
  addr = int(cols[0], 16)
- ksym_addrs.append(addr)
- ksym_names.append(name)
+ # keep a mapping of names to ksyms index
+ ksym_names[name] = len(ksyms)
+ ksyms.append((name, addr))
  syms.close()
  ksym_loaded = 1
 
  @staticmethod
  def _ksym_addr2index(addr):
- global ksym_addrs
+ global ksyms
  start = -1
- end = len(ksym_addrs)
+ end = len(ksyms)
  while end != start + 1:
  mid = int((start + end) / 2)
- if addr < ksym_addrs[mid]:
+ if addr < ksyms[mid][1]:
  end = mid
  else:
  start = mid
@@ -679,12 +680,12 @@ def ksym(addr):
  Translate a kernel memory address into a kernel function name, which is
  returned. This is a simple translator that uses /proc/kallsyms.
  """
- global ksym_names
+ global ksyms
  BPF._load_kallsyms()
  idx = BPF._ksym_addr2index(addr)
  if idx == -1:
  return "[unknown]"
- return ksym_names[idx]
+ return ksyms[idx][0]
 
  @staticmethod
  def ksymaddr(addr):
@@ -694,13 +695,27 @@ def ksymaddr(addr):
  instruction offset as a hexidecimal number, which is returned as a
  string. This is a simple translator that uses /proc/kallsyms.
  """
- global ksym_addrs, ksym_names
+ global ksyms
  BPF._load_kallsyms()
  idx = BPF._ksym_addr2index(addr)
  if idx == -1:
  return "[unknown]"
- offset = int(addr - ksym_addrs[idx])
- return ksym_names[idx] + hex(offset)
+ offset = int(addr - ksyms[idx][1])
+ return ksyms[idx][0] + hex(offset)
+
+ @staticmethod
+ def ksymname(name):
+ """ksymname(name)
+
+ Translate a kernel name into an address. This is the reverse of
+ ksymaddr. Returns -1 when the function name is unknown."""
+
+ global ksyms, ksym_names
+ BPF._load_kallsyms()
+ idx = ksym_names.get(name, -1)
+ if idx == -1:
+ return 0
+ return ksyms[idx][1]
 
  @staticmethod
  def num_open_kprobes():

src/python/bcc/table.py

@@ -186,6 +186,10 @@ def clear(self):
  for k in self.keys():
  self.__delitem__(k)
 
+ def zero(self):
+ for k in self.keys():
+ self[k] = self.Leaf()
+
  def __iter__(self):
  return TableBase.Iter(self, self.Key)
 

tools/funccount.py

@@ -65,9 +65,13 @@ def signal_ignore(signal, frame):
 int trace_count(struct pt_regs *ctx) {
  FILTER
  struct key_t key = {};
- u64 zero = 0, *val;
- key.ip = ctx->ip;
- val = counts.lookup_or_init(&key, &zero);
+ u64 *val;
+ // the kprobe pc is slightly after the function starting address, align
+ // back to the start (4 byte alignment) in order to match /proc/kallsyms
+ key.ip = ctx->ip & ~3ull;
+ val = counts.lookup(&key);
+ if (!val)
+ return 0;
  (*val)++;
  return 0;
 }
@@ -81,6 +85,16 @@ def signal_ignore(signal, frame):
 if debug:
  print(bpf_text)
 b = BPF(text=bpf_text)
+counts = b.get_table("counts")
+
+# pre-insert the function addresses into the counts table
+fns = b._get_kprobe_functions(pattern)
+for fn in fns:
+ addr = b.ksymname(fn)
+ if addr == -1:
+ raise Exception("Unknown symbol name %s" % fn)
+ counts[counts.Key(addr)] = counts.Leaf()
+
 b.attach_kprobe(event_re=pattern, fn_name="trace_count")
 matched = b.num_open_kprobes()
 if matched == 0:
@@ -106,10 +120,10 @@ def signal_ignore(signal, frame):
  print("%-8s\n" % strftime("%H:%M:%S"), end="")
 
  print("%-16s %-26s %8s" % ("ADDR", "FUNC", "COUNT"))
- counts = b.get_table("counts")
  for k, v in sorted(counts.items(), key=lambda counts: counts[1].value):
+ if v.value == 0: continue
  print("%-16x %-26s %8d" % (k.ip, b.ksym(k.ip), v.value))
- counts.clear()
+ counts.zero()
 
  if exiting:
  print("Detaching...")