Prefetcher.py revision 13772 
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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 IndirectMemoryPrefetcher(QueuedPrefetcher):
146    type = 'IndirectMemoryPrefetcher'
147    cxx_class = 'IndirectMemoryPrefetcher'
148    cxx_header = "mem/cache/prefetch/indirect_memory.hh"
149    pt_table_entries = Param.MemorySize("16",
150        "Number of entries of the Prefetch Table")
151    pt_table_assoc = Param.Unsigned(16, "Associativity of the Prefetch Table")
152    pt_table_indexing_policy = Param.BaseIndexingPolicy(
153        SetAssociative(entry_size = 1, assoc = Parent.pt_table_assoc,
154        size = Parent.pt_table_entries),
155        "Indexing policy of the pattern table")
156    pt_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
157        "Replacement policy of the pattern table")
158    max_prefetch_distance = Param.Unsigned(16, "Maximum prefetch distance")
159    max_indirect_counter_value = Param.Unsigned(8,
160        "Maximum value of the indirect counter")
161    ipd_table_entries = Param.MemorySize("4",
162        "Number of entries of the Indirect Pattern Detector")
163    ipd_table_assoc = Param.Unsigned(4,
164        "Associativity of the Indirect Pattern Detector")
165    ipd_table_indexing_policy = Param.BaseIndexingPolicy(
166        SetAssociative(entry_size = 1, assoc = Parent.ipd_table_assoc,
167        size = Parent.ipd_table_entries),
168        "Indexing policy of the Indirect Pattern Detector")
169    ipd_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
170        "Replacement policy of the Indirect Pattern Detector")
171    shift_values = VectorParam.Int([2, 3, 4, -3], "Shift values to evaluate")
172    addr_array_len = Param.Unsigned(4, "Number of misses tracked")
173    prefetch_threshold = Param.Unsigned(2,
174        "Counter threshold to start the indirect prefetching")
175    stream_counter_threshold = Param.Unsigned(4,
176        "Counter threshold to enable the stream prefetcher")
177    streaming_distance = Param.Unsigned(4,
178        "Number of prefetches to generate when using the stream prefetcher")
179
180class SignaturePathPrefetcher(QueuedPrefetcher):
181    type = 'SignaturePathPrefetcher'
182    cxx_class = 'SignaturePathPrefetcher'
183    cxx_header = "mem/cache/prefetch/signature_path.hh"
184
185    signature_shift = Param.UInt8(3,
186        "Number of bits to shift when calculating a new signature");
187    signature_bits = Param.UInt16(12,
188        "Size of the signature, in bits");
189    signature_table_entries = Param.MemorySize("1024",
190        "Number of entries of the signature table")
191    signature_table_assoc = Param.Unsigned(2,
192        "Associativity of the signature table")
193    signature_table_indexing_policy = Param.BaseIndexingPolicy(
194        SetAssociative(entry_size = 1, assoc = Parent.signature_table_assoc,
195        size = Parent.signature_table_entries),
196        "Indexing policy of the signature table")
197    signature_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
198        "Replacement policy of the signature table")
199
200    max_counter_value = Param.UInt8(7, "Maximum pattern counter value")
201    pattern_table_entries = Param.MemorySize("4096",
202        "Number of entries of the pattern table")
203    pattern_table_assoc = Param.Unsigned(1,
204        "Associativity of the pattern table")
205    strides_per_pattern_entry = Param.Unsigned(4,
206        "Number of strides stored in each pattern entry")
207    pattern_table_indexing_policy = Param.BaseIndexingPolicy(
208        SetAssociative(entry_size = 1, assoc = Parent.pattern_table_assoc,
209        size = Parent.pattern_table_entries),
210        "Indexing policy of the pattern table")
211    pattern_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
212        "Replacement policy of the pattern table")
213
214    prefetch_confidence_threshold = Param.Float(0.5,
215        "Minimum confidence to issue prefetches")
216    lookahead_confidence_threshold = Param.Float(0.75,
217        "Minimum confidence to continue exploring lookahead entries")
218
219class SignaturePathPrefetcherV2(SignaturePathPrefetcher):
220    type = 'SignaturePathPrefetcherV2'
221    cxx_class = 'SignaturePathPrefetcherV2'
222    cxx_header = "mem/cache/prefetch/signature_path_v2.hh"
223
224    signature_table_entries = "256"
225    signature_table_assoc = 1
226    pattern_table_entries = "512"
227    pattern_table_assoc = 1
228    max_counter_value = 15
229    prefetch_confidence_threshold = 0.25
230    lookahead_confidence_threshold = 0.25
231
232    global_history_register_entries = Param.MemorySize("8",
233        "Number of entries of global history register")
234    global_history_register_indexing_policy = Param.BaseIndexingPolicy(
235        SetAssociative(entry_size = 1,
236        assoc = Parent.global_history_register_entries,
237        size = Parent.global_history_register_entries),
238        "Indexing policy of the global history register")
239    global_history_register_replacement_policy = Param.BaseReplacementPolicy(
240        LRURP(), "Replacement policy of the global history register")
241
242class AccessMapPatternMatching(ClockedObject):
243    type = 'AccessMapPatternMatching'
244    cxx_class = 'AccessMapPatternMatching'
245    cxx_header = "mem/cache/prefetch/access_map_pattern_matching.hh"
246
247    block_size = Param.Unsigned(Parent.block_size,
248        "Cacheline size used by the prefetcher using this object")
249
250    limit_stride = Param.Unsigned(0,
251        "Limit the strides checked up to -X/X, if 0, disable the limit")
252    start_degree = Param.Unsigned(4,
253        "Initial degree (Maximum number of prefetches generated")
254    hot_zone_size = Param.MemorySize("2kB", "Memory covered by a hot zone")
255    access_map_table_entries = Param.MemorySize("256",
256        "Number of entries in the access map table")
257    access_map_table_assoc = Param.Unsigned(8,
258        "Associativity of the access map table")
259    access_map_table_indexing_policy = Param.BaseIndexingPolicy(
260        SetAssociative(entry_size = 1, assoc = Parent.access_map_table_assoc,
261        size = Parent.access_map_table_entries),
262        "Indexing policy of the access map table")
263    access_map_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
264        "Replacement policy of the access map table")
265    high_coverage_threshold = Param.Float(0.25,
266        "A prefetch coverage factor bigger than this is considered high")
267    low_coverage_threshold = Param.Float(0.125,
268        "A prefetch coverage factor smaller than this is considered low")
269    high_accuracy_threshold = Param.Float(0.5,
270        "A prefetch accuracy factor bigger than this is considered high")
271    low_accuracy_threshold = Param.Float(0.25,
272        "A prefetch accuracy factor smaller than this is considered low")
273    high_cache_hit_threshold = Param.Float(0.875,
274        "A cache hit ratio bigger than this is considered high")
275    low_cache_hit_threshold = Param.Float(0.75,
276        "A cache hit ratio smaller than this is considered low")
277    epoch_cycles = Param.Cycles(256000, "Cycles in an epoch period")
278    offchip_memory_latency = Param.Latency("30ns",
279        "Memory latency used to compute the required memory bandwidth")
280
281class AMPMPrefetcher(QueuedPrefetcher):
282    type = 'AMPMPrefetcher'
283    cxx_class = 'AMPMPrefetcher'
284    cxx_header = "mem/cache/prefetch/access_map_pattern_matching.hh"
285    ampm = Param.AccessMapPatternMatching( AccessMapPatternMatching(),
286        "Access Map Pattern Matching object")
287
288class DeltaCorrelatingPredictionTables(SimObject):
289    type = 'DeltaCorrelatingPredictionTables'
290    cxx_class = 'DeltaCorrelatingPredictionTables'
291    cxx_header = "mem/cache/prefetch/delta_correlating_prediction_tables.hh"
292    deltas_per_entry = Param.Unsigned(20,
293        "Number of deltas stored in each table entry")
294    delta_bits = Param.Unsigned(12, "Bits per delta")
295    delta_mask_bits = Param.Unsigned(8,
296        "Lower bits to mask when comparing deltas")
297    table_entries = Param.MemorySize("128",
298        "Number of entries in the table")
299    table_assoc = Param.Unsigned(128,
300        "Associativity of the table")
301    table_indexing_policy = Param.BaseIndexingPolicy(
302        SetAssociative(entry_size = 1, assoc = Parent.table_assoc,
303        size = Parent.table_entries),
304        "Indexing policy of the table")
305    table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
306        "Replacement policy of the table")
307
308class DCPTPrefetcher(QueuedPrefetcher):
309    type = 'DCPTPrefetcher'
310    cxx_class = 'DCPTPrefetcher'
311    cxx_header = "mem/cache/prefetch/delta_correlating_prediction_tables.hh"
312    dcpt = Param.DeltaCorrelatingPredictionTables(
313        DeltaCorrelatingPredictionTables(),
314        "Delta Correlating Prediction Tables object")
315
316class IrregularStreamBufferPrefetcher(QueuedPrefetcher):
317    type = "IrregularStreamBufferPrefetcher"
318    cxx_class = "IrregularStreamBufferPrefetcher"
319    cxx_header = "mem/cache/prefetch/irregular_stream_buffer.hh"
320
321    max_counter_value = Param.Unsigned(3,
322        "Maximum value of the confidence counter")
323    chunk_size = Param.Unsigned(256,
324        "Maximum number of addresses in a temporal stream")
325    degree = Param.Unsigned(4, "Number of prefetches to generate")
326    training_unit_assoc = Param.Unsigned(128,
327        "Associativity of the training unit")
328    training_unit_entries = Param.MemorySize("128",
329        "Number of entries of the training unit")
330    training_unit_indexing_policy = Param.BaseIndexingPolicy(
331        SetAssociative(entry_size = 1, assoc = Parent.training_unit_assoc,
332        size = Parent.training_unit_entries),
333        "Indexing policy of the training unit")
334    training_unit_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
335        "Replacement policy of the training unit")
336
337    prefetch_candidates_per_entry = Param.Unsigned(16,
338        "Number of prefetch candidates stored in a SP-AMC entry")
339    address_map_cache_assoc = Param.Unsigned(128,
340        "Associativity of the PS/SP AMCs")
341    address_map_cache_entries = Param.MemorySize("128",
342        "Number of entries of the PS/SP AMCs")
343    ps_address_map_cache_indexing_policy = Param.BaseIndexingPolicy(
344        SetAssociative(entry_size = 1,
345        assoc = Parent.address_map_cache_assoc,
346        size = Parent.address_map_cache_entries),
347        "Indexing policy of the Physical-to-Structural Address Map Cache")
348    ps_address_map_cache_replacement_policy = Param.BaseReplacementPolicy(
349        LRURP(),
350        "Replacement policy of the Physical-to-Structural Address Map Cache")
351    sp_address_map_cache_indexing_policy = Param.BaseIndexingPolicy(
352        SetAssociative(entry_size = 1,
353        assoc = Parent.address_map_cache_assoc,
354        size = Parent.address_map_cache_entries),
355        "Indexing policy of the Structural-to-Physical Address Mao Cache")
356    sp_address_map_cache_replacement_policy = Param.BaseReplacementPolicy(
357        LRURP(),
358        "Replacement policy of the Structural-to-Physical Address Map Cache")
359
360class SlimAccessMapPatternMatching(AccessMapPatternMatching):
361    start_degree = 2
362    limit_stride = 4
363
364class SlimDeltaCorrelatingPredictionTables(DeltaCorrelatingPredictionTables):
365    table_entries = "256"
366    table_assoc = 256
367    deltas_per_entry = 9
368
369class SlimAMPMPrefetcher(QueuedPrefetcher):
370    type = 'SlimAMPMPrefetcher'
371    cxx_class = 'SlimAMPMPrefetcher'
372    cxx_header = "mem/cache/prefetch/slim_ampm.hh"
373
374    ampm = Param.AccessMapPatternMatching(SlimAccessMapPatternMatching(),
375        "Access Map Pattern Matching object")
376    dcpt = Param.DeltaCorrelatingPredictionTables(
377        SlimDeltaCorrelatingPredictionTables(),
378        "Delta Correlating Prediction Tables object")
379
380class BOPPrefetcher(QueuedPrefetcher):
381    type = "BOPPrefetcher"
382    cxx_class = "BOPPrefetcher"
383    cxx_header = "mem/cache/prefetch/bop.hh"
384    score_max = Param.Unsigned(31, "Max. score to update the best offset")
385    round_max = Param.Unsigned(100, "Max. round to update the best offset")
386    bad_score = Param.Unsigned(10, "Score at which the HWP is disabled")
387    rr_size = Param.Unsigned(64, "Number of entries of each RR bank")
388    tag_bits = Param.Unsigned(12, "Bits used to store the tag")
389    offset_list_size = Param.Unsigned(46,
390                "Number of entries in the offsets list")
391    negative_offsets_enable = Param.Bool(True,
392                "Initialize the offsets list also with negative values \
393                (i.e. the table will have half of the entries with positive \
394                offsets and the other half with negative ones)")
395    delay_queue_enable = Param.Bool(True, "Enable the delay queue")
396    delay_queue_size = Param.Unsigned(15,
397                "Number of entries in the delay queue")
398    delay_queue_cycles = Param.Cycles(60,
399                "Cycles to delay a write in the left RR table from the delay \
400                queue")
401
402class SBOOEPrefetcher(QueuedPrefetcher):
403    type = 'SBOOEPrefetcher'
404    cxx_class = 'SBOOEPrefetcher'
405    cxx_header = "mem/cache/prefetch/sbooe.hh"
406    latency_buffer_size = Param.Int(32, "Entries in the latency buffer")
407    sequential_prefetchers = Param.Int(9, "Number of sequential prefetchers")
408    sandbox_entries = Param.Int(1024, "Size of the address buffer")
409    score_threshold_pct = Param.Percent(25, "Min. threshold to issue a \
410        prefetch. The value is the percentage of sandbox entries to use")
411