BloomFilters.py revision 14262:991410960fdb 
1# Copyright (c) 2019 Inria
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27# Authors: Daniel Carvalho
28
29from m5.params import *
30from m5.proxy import *
31from m5.SimObject import SimObject
32
33class BloomFilterBase(SimObject):
34    type = 'BloomFilterBase'
35    abstract = True
36    cxx_header = "base/filters/base.hh"
37    cxx_class = 'BloomFilter::Base'
38
39    size = Param.Int(4096, "Number of entries in the filter")
40
41    # By default assume that bloom filters are used for 64-byte cache lines
42    offset_bits = Param.Unsigned(6, "Number of bits in a cache line offset")
43
44    # Most of the filters are booleans, and thus saturate on 1
45    threshold = Param.Int(1, "Value at which an entry is considered as set")
46
47class BloomFilterBlock(BloomFilterBase):
48    type = 'BloomFilterBlock'
49    cxx_class = 'BloomFilter::Block'
50    cxx_header = "base/filters/block_bloom_filter.hh"
51
52    masks_lsbs = VectorParam.Unsigned([Self.offset_bits,
53        2 * Self.offset_bits], "Position of the LSB of each mask")
54    masks_sizes = VectorParam.Unsigned([Self.offset_bits, Self.offset_bits],
55        "Size, in number of bits, of each mask")
56
57class BloomFilterBulk(BloomFilterBase):
58    type = 'BloomFilterBulk'
59    cxx_class = 'BloomFilter::Bulk'
60    cxx_header = "base/filters/bulk_bloom_filter.hh"
61
62class BloomFilterLSBCounting(BloomFilterBase):
63    type = 'BloomFilterLSBCounting'
64    cxx_class = 'BloomFilter::LSBCounting'
65    cxx_header = "base/filters/lsb_counting_bloom_filter.hh"
66
67    # By default use 4-bit saturating counters
68    max_value = Param.Int(15, "Maximum value of the filter entries")
69
70    # We assume that isSet will return true only when the counter saturates
71    threshold = Self.max_value
72
73class BloomFilterMultiBitSel(BloomFilterBase):
74    type = 'BloomFilterMultiBitSel'
75    cxx_class = 'BloomFilter::MultiBitSel'
76    cxx_header = "base/filters/multi_bit_sel_bloom_filter.hh"
77
78    num_hashes = Param.Int(4, "Number of hashes")
79    threshold = Self.num_hashes
80    skip_bits = Param.Int(2, "Offset from block number")
81    is_parallel = Param.Bool(False, "Whether hashing is done in parallel")
82
83class BloomFilterH3(BloomFilterMultiBitSel):
84    type = 'BloomFilterH3'
85    cxx_class = 'BloomFilter::H3'
86    cxx_header = "base/filters/h3_bloom_filter.hh"
87
88class BloomFilterMulti(BloomFilterBase):
89    type = 'BloomFilterMulti'
90    cxx_class = 'BloomFilter::Multi'
91    cxx_header = "base/filters/multi_bloom_filter.hh"
92
93    # The base filter should not be used, since this filter is the combination
94    # of multiple sub-filters, so we use a dummy value
95    size = 1
96
97    # By default there are two sub-filters that hash sequential bitfields
98    filters = VectorParam.BloomFilterBase([
99        BloomFilterBlock(size = 4096, masks_lsbs = [6, 12]),
100        BloomFilterBlock(size = 1024, masks_lsbs = [18, 24])],
101        "Sub-filters to be combined")
102
103    # By default match this with the number of sub-filters
104    threshold = 2
105