75 lines
1.8 KiB
Python
Executable File
75 lines
1.8 KiB
Python
Executable File
#!/usr/bin/env python3
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from sys import argv
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size_classes = [
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16, 32, 48, 64, 80, 96, 112, 128,
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160, 192, 224, 256,
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320, 384, 448, 512,
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640, 768, 896, 1024,
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1280, 1536, 1792, 2048,
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2560, 3072, 3584, 4096,
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5120, 6144, 7168, 8192,
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10240, 12288, 14336, 16384
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]
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size_class_slots = [
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256, 128, 128, 64, 51, 42, 36, 64,
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51, 64, 64, 64,
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64, 64, 64, 64,
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64, 64, 64, 64,
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16, 16, 16, 16,
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8, 8, 8, 8,
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8, 8, 8, 8,
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5, 6, 4, 4
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]
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print("size class", "worst case internal fragmentation", sep=", ")
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print(16, "100%", sep=", ")
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for i in range(len(size_classes) - 1):
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size_class = size_classes[i + 1]
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worst_case = size_classes[i] + 1
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used = worst_case / size_class
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print(size_class, str(100 - used * 100) + "%", sep=", ")
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def page_align(size):
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return (size + 4095) & ~4095
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print()
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print("size class", "slab slots", "worst case internal fragmentation for slabs", sep=", ")
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for size, slots in zip(size_classes, size_class_slots):
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used = size * slots
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real = page_align(used)
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print(size, slots, str(100 - used / real * 100) + "%", sep=", ")
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if len(argv) < 2:
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exit()
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max_bits = 256
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max_page_span = 16
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print()
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print("maximum bitmap size is {}-bit".format(max_bits))
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print("maximum page span size is {} ({})".format(max_page_span, max_page_span * 4096))
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for size_class in size_classes:
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choices = []
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for bits in range(1, max_bits + 1):
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used = size_class * bits
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real = page_align(used)
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if real > 65536:
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continue
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pages = real / 4096
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efficiency = used / real * 100
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choices.append((bits, used, real, pages, efficiency))
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choices.sort(key=lambda x: x[4], reverse=True)
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print()
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print("size_class:", size_class)
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for choice in choices[:10]:
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print(choice)
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