hardened_malloc/calculate_waste.py
2018-08-23 15:42:41 -04:00

40 lines
990 B
Python
Executable File

#!/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)