added a very simple testcase for PerCpu support patch.

tests/python/test_percpu.py

+#!/usr/bin/env python
+# Copyright (c) PLUMgrid, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+from bcc import BPF
+from time import sleep
+import unittest as ut
+
+class TestPercpu(ut.TestCase):
+
+    def test_u32(self):
+        test_prog1 = """
+        BPF_TABLE("pc_array", u32, u32, stats, 1);
+        int hello_world(void *ctx) {
+            u32 key=0;
+            u32 value = 0, *val;
+            val = stats.lookup_or_init(&key, &value);
+            *val += 1;
+            return 0;
+        }
+        """
+        self.addCleanup(self.cleanup)
+        bpf_code = BPF(text=test_prog1)
+        stats_map = bpf_code.get_table("stats")
+        bpf_code.attach_kprobe(event="sys_clone", fn_name="hello_world")
+        sleep(1)
+        self.assertEqual(len(stats_map),1)
+        for x in range(0, 10):
+            ini = stats_map.Leaf(0,0,0,0,0,0,0,0)
+            stats_map[ stats_map.Key(0) ] = ini
+            sleep(1)
+            k = stats_map[ stats_map.Key(0) ]
+            x = stats_map.sum(stats_map.Key(0))
+            y = stats_map.average(stats_map.Key(0))
+            z = stats_map.max(stats_map.Key(0))
+            self.assertGreater(x.value, 1L)
+            self.assertGreater(z.value, 1L)
+
+    def test_struct_custom_func(self):
+        test_prog2 = """
+        typedef struct counter {
+        u32 c1;
+        u32 c2;
+        } counter;
+        BPF_TABLE("pc_hash", u32, counter, stats, 1);
+        int hello_world(void *ctx) {
+            u32 key=0;
+            counter value = {0,0}, *val;
+            val = stats.lookup_or_init(&key, &value);
+            val->c1 += 1;
+            val->c2 += 1;
+            return 0;
+        }
+        """
+        self.addCleanup(self.cleanup)
+        bpf_code = BPF(text=test_prog2)
+        stats_map = bpf_code.get_table("stats",
+                reducer=lambda x,y: stats_map.sLeaf(x.c1+y.c1))
+        bpf_code.attach_kprobe(event="sys_clone", fn_name="hello_world")
+        sleep(1)
+        self.assertEqual(len(stats_map),1)
+        for x in range(0, 10):
+            ini = stats_map.Leaf()
+            for i in ini:
+                i = stats_map.sLeaf(0,0)
+            stats_map[ stats_map.Key(0) ] = ini
+            sleep(1)
+            k = stats_map[ stats_map.Key(0) ]
+            self.assertGreater(k.c1, 1L)
+
+    def cleanup(self):
+        BPF.detach_kprobe("sys_clone")
+
+
+if __name__ == "__main__":
+    ut.main()
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