Add a debug mode for the KernelHeap.

zion/memory/kernel_heap.h

@@ -8,7 +8,26 @@ class KernelHeap {
 
   void* Allocate(uint64_t size);
 
+  static void DumpDistribution();
+
  private:
   uint64_t next_addr_;
   uint64_t upper_bound_;
+
+  // Distribution collection for the purpose of investigating a slab allocator.
+  // 0: 0-4B
+  // 1: 4B-8B
+  // 2: 8B-16B
+  // 3: 16B-32B
+  // 4: 32B-64B
+  // 5: 64B-128B
+  // 6: 128B-256B
+  // 7: 256B-512B
+  // 8: 512B-1KiB
+  // 9: 1KiB-2KiB
+  // 10: 2KiB-4KiB
+  // 11: 4KiB+
+  uint64_t distributions[12];
+
+  void RecordSize(uint64_t size);
 };