Cache.py revision 12726 
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39# Authors: Nathan Binkert
40#          Andreas Hansson
41
42from m5.params import *
43from m5.proxy import *
44from MemObject import MemObject
45from Prefetcher import BasePrefetcher
46from ReplacementPolicies import *
47from Tags import *
48
49
50# Enum for cache clusivity, currently mostly inclusive or mostly
51# exclusive.
52class Clusivity(Enum): vals = ['mostly_incl', 'mostly_excl']
53
54
55class BaseCache(MemObject):
56    type = 'BaseCache'
57    abstract = True
58    cxx_header = "mem/cache/base.hh"
59
60    size = Param.MemorySize("Capacity")
61    assoc = Param.Unsigned("Associativity")
62
63    tag_latency = Param.Cycles("Tag lookup latency")
64    data_latency = Param.Cycles("Data access latency")
65    response_latency = Param.Cycles("Latency for the return path on a miss");
66
67    warmup_percentage = Param.Percent(0,
68        "Percentage of tags to be touched to warm up the cache")
69
70    max_miss_count = Param.Counter(0,
71        "Number of misses to handle before calling exit")
72
73    mshrs = Param.Unsigned("Number of MSHRs (max outstanding requests)")
74    demand_mshr_reserve = Param.Unsigned(1, "MSHRs reserved for demand access")
75    tgts_per_mshr = Param.Unsigned("Max number of accesses per MSHR")
76    write_buffers = Param.Unsigned(8, "Number of write buffers")
77
78    is_read_only = Param.Bool(False, "Is this cache read only (e.g. inst)")
79
80    prefetcher = Param.BasePrefetcher(NULL,"Prefetcher attached to cache")
81    prefetch_on_access = Param.Bool(False,
82         "Notify the hardware prefetcher on every access (not just misses)")
83
84    tags = Param.BaseTags(BaseSetAssoc(), "Tag store")
85    replacement_policy = Param.BaseReplacementPolicy(LRURP(),
86        "Replacement policy")
87
88    sequential_access = Param.Bool(False,
89        "Whether to access tags and data sequentially")
90
91    cpu_side = SlavePort("Upstream port closer to the CPU and/or device")
92    mem_side = MasterPort("Downstream port closer to memory")
93
94    addr_ranges = VectorParam.AddrRange([AllMemory],
95         "Address range for the CPU-side port (to allow striping)")
96
97    system = Param.System(Parent.any, "System we belong to")
98
99    # Determine if this cache sends out writebacks for clean lines, or
100    # simply clean evicts. In cases where a downstream cache is mostly
101    # exclusive with respect to this cache (acting as a victim cache),
102    # the clean writebacks are essential for performance. In general
103    # this should be set to True for anything but the last-level
104    # cache.
105    writeback_clean = Param.Bool(False, "Writeback clean lines")
106
107    # Control whether this cache should be mostly inclusive or mostly
108    # exclusive with respect to upstream caches. The behaviour on a
109    # fill is determined accordingly. For a mostly inclusive cache,
110    # blocks are allocated on all fill operations. Thus, L1 caches
111    # should be set as mostly inclusive even if they have no upstream
112    # caches. In the case of a mostly exclusive cache, fills are not
113    # allocating unless they came directly from a non-caching source,
114    # e.g. a table walker. Additionally, on a hit from an upstream
115    # cache a line is dropped for a mostly exclusive cache.
116    clusivity = Param.Clusivity('mostly_incl',
117                                "Clusivity with upstream cache")
118
119
120class Cache(BaseCache):
121    type = 'Cache'
122    cxx_header = 'mem/cache/cache.hh'
123
124
125class NoncoherentCache(BaseCache):
126    type = 'NoncoherentCache'
127    cxx_header = 'mem/cache/noncoherent_cache.hh'
128
129    # This is typically a last level cache and any clean
130    # writebacks would be unnecessary traffic to the main memory.
131    writeback_clean = False
132
133