Support for hotplug cpu cases in percpu array sizing

The kernel uses number of possible cpus to size the leaf, not the num of
online cpus. Fixup the python side appropriately.
Update: use num_possible_cpus() helper instead
Signed-off-by: Brenden Blanco <bblanco@gmail.com>

src/python/bcc/table.py

@@ -21,6 +21,7 @@ import os
 from .libbcc import lib, _RAW_CB_TYPE
 from .perf import Perf
 from .utils import get_online_cpus
+from .utils import get_possible_cpus
 from subprocess import check_output
 
 BPF_MAP_TYPE_HASH = 1
@@ -561,7 +562,7 @@ class PerCpuHash(HashTable):
         self.reducer = kwargs.pop("reducer", None)
         super(PerCpuHash, self).__init__(*args, **kwargs)
         self.sLeaf = self.Leaf
-        self.total_cpu = multiprocessing.cpu_count()
+        self.total_cpu = len(get_possible_cpus())
         # This needs to be 8 as hard coded into the linux kernel.
         self.alignment = ct.sizeof(self.sLeaf) % 8
         if self.alignment is 0:
@@ -617,7 +618,7 @@ class PerCpuArray(ArrayBase):
         self.reducer = kwargs.pop("reducer", None)
         super(PerCpuArray, self).__init__(*args, **kwargs)
         self.sLeaf = self.Leaf
-        self.total_cpu = multiprocessing.cpu_count()
+        self.total_cpu = len(get_possible_cpus())
         # This needs to be 8 as hard coded into the linux kernel.
         self.alignment = ct.sizeof(self.sLeaf) % 8
         if self.alignment is 0: