Add a debug mode for the KernelHeap.

zion/memory/kernel_heap.cpp

@@ -3,6 +3,8 @@
 #include "debug/debug.h"
 #include "memory/paging_util.h"
 
+#define K_HEAP_DEBUG 0
+
 namespace {
 
 static KernelHeap* gKernelHeap = nullptr;
@@ -24,12 +26,43 @@ void* KernelHeap::Allocate(uint64_t size) {
   if (next_addr_ + size >= upper_bound_) {
     panic("Kernel Heap Overrun");
   }
+#if K_HEAP_DEBUG
+  RecordSize(size);
+#endif
   EnsureResident(next_addr_, size);
   uint64_t address = next_addr_;
   next_addr_ += size;
   return reinterpret_cast<void*>(address);
 }
 
+void KernelHeap::DumpDistribution() {
+#if K_HEAP_DEBUG
+  uint64_t* distributions = gKernelHeap->distributions;
+  dbgln("<=4B:   %u", distributions[0]);
+  dbgln("<=8B:   %u", distributions[1]);
+  dbgln("<=16B:  %u", distributions[2]);
+  dbgln("<=32B:  %u", distributions[3]);
+  dbgln("<=64B:  %u", distributions[4]);
+  dbgln("<=128B: %u", distributions[5]);
+  dbgln("<=256B: %u", distributions[6]);
+  dbgln("<=512B: %u", distributions[7]);
+  dbgln("<=1KiB: %u", distributions[8]);
+  dbgln("<=2KiB: %u", distributions[9]);
+  dbgln("<=4KiB: %u", distributions[10]);
+  dbgln("> 4KiB: %u", distributions[11]);
+#endif
+}
+
+void KernelHeap::RecordSize(uint64_t size) {
+  size >>= 3;
+  uint64_t index = 0;
+  while (size && index < 11) {
+    size >>= 1;
+    index++;
+  }
+  distributions[index]++;
+}
+
 void* operator new(uint64_t size) { return GetKernelHeap().Allocate(size); }
 void* operator new[](uint64_t size) { return GetKernelHeap().Allocate(size); }
 

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);
 };