Prefetcher.py revision 13700 
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13# Copyright (c) 2005 The Regents of The University of Michigan
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38#
39# Authors: Ron Dreslinski
40#          Mitch Hayenga
41
42from m5.SimObject import *
43from m5.params import *
44from m5.proxy import *
45
46from m5.objects.ClockedObject import ClockedObject
47from m5.objects.IndexingPolicies import *
48from m5.objects.ReplacementPolicies import *
49
50class HWPProbeEvent(object):
51    def __init__(self, prefetcher, obj, *listOfNames):
52        self.obj = obj
53        self.prefetcher = prefetcher
54        self.names = listOfNames
55
56    def register(self):
57        if self.obj:
58            for name in self.names:
59                self.prefetcher.getCCObject().addEventProbe(
60                    self.obj.getCCObject(), name)
61
62class BasePrefetcher(ClockedObject):
63    type = 'BasePrefetcher'
64    abstract = True
65    cxx_header = "mem/cache/prefetch/base.hh"
66    cxx_exports = [
67        PyBindMethod("addEventProbe"),
68    ]
69    sys = Param.System(Parent.any, "System this prefetcher belongs to")
70
71    # Get the block size from the parent (system)
72    block_size = Param.Int(Parent.cache_line_size, "Block size in bytes")
73
74    on_miss = Param.Bool(False, "Only notify prefetcher on misses")
75    on_read = Param.Bool(True, "Notify prefetcher on reads")
76    on_write = Param.Bool(True, "Notify prefetcher on writes")
77    on_data  = Param.Bool(True, "Notify prefetcher on data accesses")
78    on_inst  = Param.Bool(True, "Notify prefetcher on instruction accesses")
79    prefetch_on_access = Param.Bool(Parent.prefetch_on_access,
80        "Notify the hardware prefetcher on every access (not just misses)")
81    use_virtual_addresses = Param.Bool(False,
82        "Use virtual addresses for prefetching")
83
84    _events = []
85    def addEvent(self, newObject):
86        self._events.append(newObject)
87
88    # Override the normal SimObject::regProbeListeners method and
89    # register deferred event handlers.
90    def regProbeListeners(self):
91        for event in self._events:
92           event.register()
93        self.getCCObject().regProbeListeners()
94
95    def listenFromProbe(self, simObj, *probeNames):
96        if not isinstance(simObj, SimObject):
97            raise TypeError("argument must be of SimObject type")
98        if len(probeNames) <= 0:
99            raise TypeError("probeNames must have at least one element")
100        self.addEvent(HWPProbeEvent(self, simObj, *probeNames))
101
102class QueuedPrefetcher(BasePrefetcher):
103    type = "QueuedPrefetcher"
104    abstract = True
105    cxx_class = "QueuedPrefetcher"
106    cxx_header = "mem/cache/prefetch/queued.hh"
107    latency = Param.Int(1, "Latency for generated prefetches")
108    queue_size = Param.Int(32, "Maximum number of queued prefetches")
109    queue_squash = Param.Bool(True, "Squash queued prefetch on demand access")
110    queue_filter = Param.Bool(True, "Don't queue redundant prefetches")
111    cache_snoop = Param.Bool(False, "Snoop cache to eliminate redundant request")
112
113    tag_prefetch = Param.Bool(True, "Tag prefetch with PC of generating access")
114
115class StridePrefetcher(QueuedPrefetcher):
116    type = 'StridePrefetcher'
117    cxx_class = 'StridePrefetcher'
118    cxx_header = "mem/cache/prefetch/stride.hh"
119
120    # Do not consult stride prefetcher on instruction accesses
121    on_inst = False
122
123    max_conf = Param.Int(7, "Maximum confidence level")
124    thresh_conf = Param.Int(4, "Threshold confidence level")
125    min_conf = Param.Int(0, "Minimum confidence level")
126    start_conf = Param.Int(4, "Starting confidence for new entries")
127
128    table_sets = Param.Int(16, "Number of sets in PC lookup table")
129    table_assoc = Param.Int(4, "Associativity of PC lookup table")
130    use_master_id = Param.Bool(True, "Use master id based history")
131
132    degree = Param.Int(4, "Number of prefetches to generate")
133
134    # Get replacement policy
135    replacement_policy = Param.BaseReplacementPolicy(RandomRP(),
136        "Replacement policy")
137
138class TaggedPrefetcher(QueuedPrefetcher):
139    type = 'TaggedPrefetcher'
140    cxx_class = 'TaggedPrefetcher'
141    cxx_header = "mem/cache/prefetch/tagged.hh"
142
143    degree = Param.Int(2, "Number of prefetches to generate")
144
145class SignaturePathPrefetcher(QueuedPrefetcher):
146    type = 'SignaturePathPrefetcher'
147    cxx_class = 'SignaturePathPrefetcher'
148    cxx_header = "mem/cache/prefetch/signature_path.hh"
149
150    signature_shift = Param.UInt8(3,
151        "Number of bits to shift when calculating a new signature");
152    signature_bits = Param.UInt16(12,
153        "Size of the signature, in bits");
154    signature_table_entries = Param.MemorySize("1024",
155        "Number of entries of the signature table")
156    signature_table_assoc = Param.Unsigned(2,
157        "Associativity of the signature table")
158    signature_table_indexing_policy = Param.BaseIndexingPolicy(
159        SetAssociative(entry_size = 1, assoc = Parent.signature_table_assoc,
160        size = Parent.signature_table_entries),
161        "Indexing policy of the signature table")
162    signature_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
163        "Replacement policy of the signature table")
164
165    max_counter_value = Param.UInt8(7, "Maximum pattern counter value")
166    pattern_table_entries = Param.MemorySize("4096",
167        "Number of entries of the pattern table")
168    pattern_table_assoc = Param.Unsigned(1,
169        "Associativity of the pattern table")
170    strides_per_pattern_entry = Param.Unsigned(4,
171        "Number of strides stored in each pattern entry")
172    pattern_table_indexing_policy = Param.BaseIndexingPolicy(
173        SetAssociative(entry_size = 1, assoc = Parent.pattern_table_assoc,
174        size = Parent.pattern_table_entries),
175        "Indexing policy of the pattern table")
176    pattern_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
177        "Replacement policy of the pattern table")
178
179    prefetch_confidence_threshold = Param.Float(0.5,
180        "Minimum confidence to issue prefetches")
181    lookahead_confidence_threshold = Param.Float(0.75,
182        "Minimum confidence to continue exploring lookahead entries")
183
184class SignaturePathPrefetcherV2(SignaturePathPrefetcher):
185    type = 'SignaturePathPrefetcherV2'
186    cxx_class = 'SignaturePathPrefetcherV2'
187    cxx_header = "mem/cache/prefetch/signature_path_v2.hh"
188
189    signature_table_entries = "256"
190    signature_table_assoc = 1
191    pattern_table_entries = "512"
192    pattern_table_assoc = 1
193    max_counter_value = 15
194    prefetch_confidence_threshold = 0.25
195    lookahead_confidence_threshold = 0.25
196
197    global_history_register_entries = Param.MemorySize("8",
198        "Number of entries of global history register")
199    global_history_register_indexing_policy = Param.BaseIndexingPolicy(
200        SetAssociative(entry_size = 1,
201        assoc = Parent.global_history_register_entries,
202        size = Parent.global_history_register_entries),
203        "Indexing policy of the global history register")
204    global_history_register_replacement_policy = Param.BaseReplacementPolicy(
205        LRURP(), "Replacement policy of the global history register")
206
207class AccessMapPatternMatching(ClockedObject):
208    type = 'AccessMapPatternMatching'
209    cxx_class = 'AccessMapPatternMatching'
210    cxx_header = "mem/cache/prefetch/access_map_pattern_matching.hh"
211
212    block_size = Param.Unsigned(Parent.block_size,
213        "Cacheline size used by the prefetcher using this object")
214
215    limit_stride = Param.Unsigned(0,
216        "Limit the strides checked up to -X/X, if 0, disable the limit")
217    start_degree = Param.Unsigned(4,
218        "Initial degree (Maximum number of prefetches generated")
219    hot_zone_size = Param.MemorySize("2kB", "Memory covered by a hot zone")
220    access_map_table_entries = Param.MemorySize("256",
221        "Number of entries in the access map table")
222    access_map_table_assoc = Param.Unsigned(8,
223        "Associativity of the access map table")
224    access_map_table_indexing_policy = Param.BaseIndexingPolicy(
225        SetAssociative(entry_size = 1, assoc = Parent.access_map_table_assoc,
226        size = Parent.access_map_table_entries),
227        "Indexing policy of the access map table")
228    access_map_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
229        "Replacement policy of the access map table")
230    high_coverage_threshold = Param.Float(0.25,
231        "A prefetch coverage factor bigger than this is considered high")
232    low_coverage_threshold = Param.Float(0.125,
233        "A prefetch coverage factor smaller than this is considered low")
234    high_accuracy_threshold = Param.Float(0.5,
235        "A prefetch accuracy factor bigger than this is considered high")
236    low_accuracy_threshold = Param.Float(0.25,
237        "A prefetch accuracy factor smaller than this is considered low")
238    high_cache_hit_threshold = Param.Float(0.875,
239        "A cache hit ratio bigger than this is considered high")
240    low_cache_hit_threshold = Param.Float(0.75,
241        "A cache hit ratio smaller than this is considered low")
242    epoch_cycles = Param.Cycles(256000, "Cycles in an epoch period")
243    offchip_memory_latency = Param.Latency("30ns",
244        "Memory latency used to compute the required memory bandwidth")
245
246class AMPMPrefetcher(QueuedPrefetcher):
247    type = 'AMPMPrefetcher'
248    cxx_class = 'AMPMPrefetcher'
249    cxx_header = "mem/cache/prefetch/access_map_pattern_matching.hh"
250    ampm = Param.AccessMapPatternMatching( AccessMapPatternMatching(),
251        "Access Map Pattern Matching object")
252
253class DeltaCorrelatingPredictionTables(SimObject):
254    type = 'DeltaCorrelatingPredictionTables'
255    cxx_class = 'DeltaCorrelatingPredictionTables'
256    cxx_header = "mem/cache/prefetch/delta_correlating_prediction_tables.hh"
257    deltas_per_entry = Param.Unsigned(20,
258        "Number of deltas stored in each table entry")
259    delta_bits = Param.Unsigned(12, "Bits per delta")
260    delta_mask_bits = Param.Unsigned(8,
261        "Lower bits to mask when comparing deltas")
262    table_entries = Param.MemorySize("128",
263        "Number of entries in the table")
264    table_assoc = Param.Unsigned(128,
265        "Associativity of the table")
266    table_indexing_policy = Param.BaseIndexingPolicy(
267        SetAssociative(entry_size = 1, assoc = Parent.table_assoc,
268        size = Parent.table_entries),
269        "Indexing policy of the table")
270    table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
271        "Replacement policy of the table")
272
273class DCPTPrefetcher(QueuedPrefetcher):
274    type = 'DCPTPrefetcher'
275    cxx_class = 'DCPTPrefetcher'
276    cxx_header = "mem/cache/prefetch/delta_correlating_prediction_tables.hh"
277    dcpt = Param.DeltaCorrelatingPredictionTables(
278        DeltaCorrelatingPredictionTables(),
279        "Delta Correlating Prediction Tables object")
280
281class IrregularStreamBufferPrefetcher(QueuedPrefetcher):
282    type = "IrregularStreamBufferPrefetcher"
283    cxx_class = "IrregularStreamBufferPrefetcher"
284    cxx_header = "mem/cache/prefetch/irregular_stream_buffer.hh"
285
286    max_counter_value = Param.Unsigned(3,
287        "Maximum value of the confidence counter")
288    chunk_size = Param.Unsigned(256,
289        "Maximum number of addresses in a temporal stream")
290    degree = Param.Unsigned(4, "Number of prefetches to generate")
291    training_unit_assoc = Param.Unsigned(128,
292        "Associativity of the training unit")
293    training_unit_entries = Param.MemorySize("128",
294        "Number of entries of the training unit")
295    training_unit_indexing_policy = Param.BaseIndexingPolicy(
296        SetAssociative(entry_size = 1, assoc = Parent.training_unit_assoc,
297        size = Parent.training_unit_entries),
298        "Indexing policy of the training unit")
299    training_unit_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
300        "Replacement policy of the training unit")
301
302    prefetch_candidates_per_entry = Param.Unsigned(16,
303        "Number of prefetch candidates stored in a SP-AMC entry")
304    address_map_cache_assoc = Param.Unsigned(128,
305        "Associativity of the PS/SP AMCs")
306    address_map_cache_entries = Param.MemorySize("128",
307        "Number of entries of the PS/SP AMCs")
308    ps_address_map_cache_indexing_policy = Param.BaseIndexingPolicy(
309        SetAssociative(entry_size = 1,
310        assoc = Parent.address_map_cache_assoc,
311        size = Parent.address_map_cache_entries),
312        "Indexing policy of the Physical-to-Structural Address Map Cache")
313    ps_address_map_cache_replacement_policy = Param.BaseReplacementPolicy(
314        LRURP(),
315        "Replacement policy of the Physical-to-Structural Address Map Cache")
316    sp_address_map_cache_indexing_policy = Param.BaseIndexingPolicy(
317        SetAssociative(entry_size = 1,
318        assoc = Parent.address_map_cache_assoc,
319        size = Parent.address_map_cache_entries),
320        "Indexing policy of the Structural-to-Physical Address Mao Cache")
321    sp_address_map_cache_replacement_policy = Param.BaseReplacementPolicy(
322        LRURP(),
323        "Replacement policy of the Structural-to-Physical Address Map Cache")
324
325class SlimAccessMapPatternMatching(AccessMapPatternMatching):
326    start_degree = 2
327    limit_stride = 4
328
329class SlimDeltaCorrelatingPredictionTables(DeltaCorrelatingPredictionTables):
330    table_entries = "256"
331    table_assoc = 256
332    deltas_per_entry = 9
333
334class SlimAMPMPrefetcher(QueuedPrefetcher):
335    type = 'SlimAMPMPrefetcher'
336    cxx_class = 'SlimAMPMPrefetcher'
337    cxx_header = "mem/cache/prefetch/slim_ampm.hh"
338
339    ampm = Param.AccessMapPatternMatching(SlimAccessMapPatternMatching(),
340        "Access Map Pattern Matching object")
341    dcpt = Param.DeltaCorrelatingPredictionTables(
342        SlimDeltaCorrelatingPredictionTables(),
343        "Delta Correlating Prediction Tables object")
344