initial commit

calculate_waste.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+
+size_classes = [
+    16, 32, 48, 64, 80, 96, 112, 128,
+    160, 192, 224, 256,
+    320, 384, 448, 512,
+    640, 768, 896, 1024,
+    1280, 1536, 1792, 2048,
+    2560, 3072, 3584, 4096,
+    5120, 6144, 7168, 8192,
+    10240, 12288, 14336, 16384
+]
+
+def page_align(size):
+    return (size + 4095) & ~4095
+
+max_bits = 256
+max_page_span = 16
+
+print("maximum bitmap size is {}-bit".format(max_bits))
+print("maximum page span size is {} ({})".format(max_page_span, max_page_span * 4096))
+
+for size_class in size_classes:
+    choices = []
+    for bits in range(1, max_bits + 1):
+        used = size_class * bits
+        real = page_align(used)
+        if real > 65536:
+            continue
+        pages = real / 4096
+        efficiency = used / real * 100
+        choices.append((bits, used, real, pages, efficiency))
+
+    choices.sort(key=lambda x: x[4], reverse=True)
+
+    print()
+    print("size_class:", size_class)
+    for choice in choices[:10]:
+        print(choice)