Prefetcher.py revision 13991 
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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 MultiPrefetcher(BasePrefetcher):
103    type = 'MultiPrefetcher'
104    cxx_class = 'MultiPrefetcher'
105    cxx_header = 'mem/cache/prefetch/multi.hh'
106
107    prefetchers = VectorParam.BasePrefetcher([], "Array of prefetchers")
108
109class QueuedPrefetcher(BasePrefetcher):
110    type = "QueuedPrefetcher"
111    abstract = True
112    cxx_class = "QueuedPrefetcher"
113    cxx_header = "mem/cache/prefetch/queued.hh"
114    latency = Param.Int(1, "Latency for generated prefetches")
115    queue_size = Param.Int(32, "Maximum number of queued prefetches")
116    queue_squash = Param.Bool(True, "Squash queued prefetch on demand access")
117    queue_filter = Param.Bool(True, "Don't queue redundant prefetches")
118    cache_snoop = Param.Bool(False, "Snoop cache to eliminate redundant request")
119
120    tag_prefetch = Param.Bool(True, "Tag prefetch with PC of generating access")
121
122class StridePrefetcher(QueuedPrefetcher):
123    type = 'StridePrefetcher'
124    cxx_class = 'StridePrefetcher'
125    cxx_header = "mem/cache/prefetch/stride.hh"
126
127    # Do not consult stride prefetcher on instruction accesses
128    on_inst = False
129
130    max_conf = Param.Int(7, "Maximum confidence level")
131    thresh_conf = Param.Int(4, "Threshold confidence level")
132    min_conf = Param.Int(0, "Minimum confidence level")
133    start_conf = Param.Int(4, "Starting confidence for new entries")
134
135    table_sets = Param.Int(16, "Number of sets in PC lookup table")
136    table_assoc = Param.Int(4, "Associativity of PC lookup table")
137    use_master_id = Param.Bool(True, "Use master id based history")
138
139    degree = Param.Int(4, "Number of prefetches to generate")
140
141    # Get replacement policy
142    replacement_policy = Param.BaseReplacementPolicy(RandomRP(),
143        "Replacement policy")
144
145class TaggedPrefetcher(QueuedPrefetcher):
146    type = 'TaggedPrefetcher'
147    cxx_class = 'TaggedPrefetcher'
148    cxx_header = "mem/cache/prefetch/tagged.hh"
149
150    degree = Param.Int(2, "Number of prefetches to generate")
151
152class IndirectMemoryPrefetcher(QueuedPrefetcher):
153    type = 'IndirectMemoryPrefetcher'
154    cxx_class = 'IndirectMemoryPrefetcher'
155    cxx_header = "mem/cache/prefetch/indirect_memory.hh"
156    pt_table_entries = Param.MemorySize("16",
157        "Number of entries of the Prefetch Table")
158    pt_table_assoc = Param.Unsigned(16, "Associativity of the Prefetch Table")
159    pt_table_indexing_policy = Param.BaseIndexingPolicy(
160        SetAssociative(entry_size = 1, assoc = Parent.pt_table_assoc,
161        size = Parent.pt_table_entries),
162        "Indexing policy of the pattern table")
163    pt_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
164        "Replacement policy of the pattern table")
165    max_prefetch_distance = Param.Unsigned(16, "Maximum prefetch distance")
166    num_indirect_counter_bits = Param.Unsigned(3,
167        "Number of bits of the indirect counter")
168    ipd_table_entries = Param.MemorySize("4",
169        "Number of entries of the Indirect Pattern Detector")
170    ipd_table_assoc = Param.Unsigned(4,
171        "Associativity of the Indirect Pattern Detector")
172    ipd_table_indexing_policy = Param.BaseIndexingPolicy(
173        SetAssociative(entry_size = 1, assoc = Parent.ipd_table_assoc,
174        size = Parent.ipd_table_entries),
175        "Indexing policy of the Indirect Pattern Detector")
176    ipd_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
177        "Replacement policy of the Indirect Pattern Detector")
178    shift_values = VectorParam.Int([2, 3, 4, -3], "Shift values to evaluate")
179    addr_array_len = Param.Unsigned(4, "Number of misses tracked")
180    prefetch_threshold = Param.Unsigned(2,
181        "Counter threshold to start the indirect prefetching")
182    stream_counter_threshold = Param.Unsigned(4,
183        "Counter threshold to enable the stream prefetcher")
184    streaming_distance = Param.Unsigned(4,
185        "Number of prefetches to generate when using the stream prefetcher")
186
187class SignaturePathPrefetcher(QueuedPrefetcher):
188    type = 'SignaturePathPrefetcher'
189    cxx_class = 'SignaturePathPrefetcher'
190    cxx_header = "mem/cache/prefetch/signature_path.hh"
191
192    signature_shift = Param.UInt8(3,
193        "Number of bits to shift when calculating a new signature");
194    signature_bits = Param.UInt16(12,
195        "Size of the signature, in bits");
196    signature_table_entries = Param.MemorySize("1024",
197        "Number of entries of the signature table")
198    signature_table_assoc = Param.Unsigned(2,
199        "Associativity of the signature table")
200    signature_table_indexing_policy = Param.BaseIndexingPolicy(
201        SetAssociative(entry_size = 1, assoc = Parent.signature_table_assoc,
202        size = Parent.signature_table_entries),
203        "Indexing policy of the signature table")
204    signature_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
205        "Replacement policy of the signature table")
206
207    num_counter_bits = Param.UInt8(3,
208        "Number of bits of the saturating counters")
209    pattern_table_entries = Param.MemorySize("4096",
210        "Number of entries of the pattern table")
211    pattern_table_assoc = Param.Unsigned(1,
212        "Associativity of the pattern table")
213    strides_per_pattern_entry = Param.Unsigned(4,
214        "Number of strides stored in each pattern entry")
215    pattern_table_indexing_policy = Param.BaseIndexingPolicy(
216        SetAssociative(entry_size = 1, assoc = Parent.pattern_table_assoc,
217        size = Parent.pattern_table_entries),
218        "Indexing policy of the pattern table")
219    pattern_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
220        "Replacement policy of the pattern table")
221
222    prefetch_confidence_threshold = Param.Float(0.5,
223        "Minimum confidence to issue prefetches")
224    lookahead_confidence_threshold = Param.Float(0.75,
225        "Minimum confidence to continue exploring lookahead entries")
226
227class SignaturePathPrefetcherV2(SignaturePathPrefetcher):
228    type = 'SignaturePathPrefetcherV2'
229    cxx_class = 'SignaturePathPrefetcherV2'
230    cxx_header = "mem/cache/prefetch/signature_path_v2.hh"
231
232    signature_table_entries = "256"
233    signature_table_assoc = 1
234    pattern_table_entries = "512"
235    pattern_table_assoc = 1
236    num_counter_bits = 4
237    prefetch_confidence_threshold = 0.25
238    lookahead_confidence_threshold = 0.25
239
240    global_history_register_entries = Param.MemorySize("8",
241        "Number of entries of global history register")
242    global_history_register_indexing_policy = Param.BaseIndexingPolicy(
243        SetAssociative(entry_size = 1,
244        assoc = Parent.global_history_register_entries,
245        size = Parent.global_history_register_entries),
246        "Indexing policy of the global history register")
247    global_history_register_replacement_policy = Param.BaseReplacementPolicy(
248        LRURP(), "Replacement policy of the global history register")
249
250class AccessMapPatternMatching(ClockedObject):
251    type = 'AccessMapPatternMatching'
252    cxx_class = 'AccessMapPatternMatching'
253    cxx_header = "mem/cache/prefetch/access_map_pattern_matching.hh"
254
255    block_size = Param.Unsigned(Parent.block_size,
256        "Cacheline size used by the prefetcher using this object")
257
258    limit_stride = Param.Unsigned(0,
259        "Limit the strides checked up to -X/X, if 0, disable the limit")
260    start_degree = Param.Unsigned(4,
261        "Initial degree (Maximum number of prefetches generated")
262    hot_zone_size = Param.MemorySize("2kB", "Memory covered by a hot zone")
263    access_map_table_entries = Param.MemorySize("256",
264        "Number of entries in the access map table")
265    access_map_table_assoc = Param.Unsigned(8,
266        "Associativity of the access map table")
267    access_map_table_indexing_policy = Param.BaseIndexingPolicy(
268        SetAssociative(entry_size = 1, assoc = Parent.access_map_table_assoc,
269        size = Parent.access_map_table_entries),
270        "Indexing policy of the access map table")
271    access_map_table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
272        "Replacement policy of the access map table")
273    high_coverage_threshold = Param.Float(0.25,
274        "A prefetch coverage factor bigger than this is considered high")
275    low_coverage_threshold = Param.Float(0.125,
276        "A prefetch coverage factor smaller than this is considered low")
277    high_accuracy_threshold = Param.Float(0.5,
278        "A prefetch accuracy factor bigger than this is considered high")
279    low_accuracy_threshold = Param.Float(0.25,
280        "A prefetch accuracy factor smaller than this is considered low")
281    high_cache_hit_threshold = Param.Float(0.875,
282        "A cache hit ratio bigger than this is considered high")
283    low_cache_hit_threshold = Param.Float(0.75,
284        "A cache hit ratio smaller than this is considered low")
285    epoch_cycles = Param.Cycles(256000, "Cycles in an epoch period")
286    offchip_memory_latency = Param.Latency("30ns",
287        "Memory latency used to compute the required memory bandwidth")
288
289class AMPMPrefetcher(QueuedPrefetcher):
290    type = 'AMPMPrefetcher'
291    cxx_class = 'AMPMPrefetcher'
292    cxx_header = "mem/cache/prefetch/access_map_pattern_matching.hh"
293    ampm = Param.AccessMapPatternMatching( AccessMapPatternMatching(),
294        "Access Map Pattern Matching object")
295
296class DeltaCorrelatingPredictionTables(SimObject):
297    type = 'DeltaCorrelatingPredictionTables'
298    cxx_class = 'DeltaCorrelatingPredictionTables'
299    cxx_header = "mem/cache/prefetch/delta_correlating_prediction_tables.hh"
300    deltas_per_entry = Param.Unsigned(20,
301        "Number of deltas stored in each table entry")
302    delta_bits = Param.Unsigned(12, "Bits per delta")
303    delta_mask_bits = Param.Unsigned(8,
304        "Lower bits to mask when comparing deltas")
305    table_entries = Param.MemorySize("128",
306        "Number of entries in the table")
307    table_assoc = Param.Unsigned(128,
308        "Associativity of the table")
309    table_indexing_policy = Param.BaseIndexingPolicy(
310        SetAssociative(entry_size = 1, assoc = Parent.table_assoc,
311        size = Parent.table_entries),
312        "Indexing policy of the table")
313    table_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
314        "Replacement policy of the table")
315
316class DCPTPrefetcher(QueuedPrefetcher):
317    type = 'DCPTPrefetcher'
318    cxx_class = 'DCPTPrefetcher'
319    cxx_header = "mem/cache/prefetch/delta_correlating_prediction_tables.hh"
320    dcpt = Param.DeltaCorrelatingPredictionTables(
321        DeltaCorrelatingPredictionTables(),
322        "Delta Correlating Prediction Tables object")
323
324class IrregularStreamBufferPrefetcher(QueuedPrefetcher):
325    type = "IrregularStreamBufferPrefetcher"
326    cxx_class = "IrregularStreamBufferPrefetcher"
327    cxx_header = "mem/cache/prefetch/irregular_stream_buffer.hh"
328
329    num_counter_bits = Param.Unsigned(2,
330        "Number of bits of the confidence counter")
331    chunk_size = Param.Unsigned(256,
332        "Maximum number of addresses in a temporal stream")
333    degree = Param.Unsigned(4, "Number of prefetches to generate")
334    training_unit_assoc = Param.Unsigned(128,
335        "Associativity of the training unit")
336    training_unit_entries = Param.MemorySize("128",
337        "Number of entries of the training unit")
338    training_unit_indexing_policy = Param.BaseIndexingPolicy(
339        SetAssociative(entry_size = 1, assoc = Parent.training_unit_assoc,
340        size = Parent.training_unit_entries),
341        "Indexing policy of the training unit")
342    training_unit_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
343        "Replacement policy of the training unit")
344
345    prefetch_candidates_per_entry = Param.Unsigned(16,
346        "Number of prefetch candidates stored in a SP-AMC entry")
347    address_map_cache_assoc = Param.Unsigned(128,
348        "Associativity of the PS/SP AMCs")
349    address_map_cache_entries = Param.MemorySize("128",
350        "Number of entries of the PS/SP AMCs")
351    ps_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 Physical-to-Structural Address Map Cache")
356    ps_address_map_cache_replacement_policy = Param.BaseReplacementPolicy(
357        LRURP(),
358        "Replacement policy of the Physical-to-Structural Address Map Cache")
359    sp_address_map_cache_indexing_policy = Param.BaseIndexingPolicy(
360        SetAssociative(entry_size = 1,
361        assoc = Parent.address_map_cache_assoc,
362        size = Parent.address_map_cache_entries),
363        "Indexing policy of the Structural-to-Physical Address Mao Cache")
364    sp_address_map_cache_replacement_policy = Param.BaseReplacementPolicy(
365        LRURP(),
366        "Replacement policy of the Structural-to-Physical Address Map Cache")
367
368class SlimAccessMapPatternMatching(AccessMapPatternMatching):
369    start_degree = 2
370    limit_stride = 4
371
372class SlimDeltaCorrelatingPredictionTables(DeltaCorrelatingPredictionTables):
373    table_entries = "256"
374    table_assoc = 256
375    deltas_per_entry = 9
376
377class SlimAMPMPrefetcher(QueuedPrefetcher):
378    type = 'SlimAMPMPrefetcher'
379    cxx_class = 'SlimAMPMPrefetcher'
380    cxx_header = "mem/cache/prefetch/slim_ampm.hh"
381
382    ampm = Param.AccessMapPatternMatching(SlimAccessMapPatternMatching(),
383        "Access Map Pattern Matching object")
384    dcpt = Param.DeltaCorrelatingPredictionTables(
385        SlimDeltaCorrelatingPredictionTables(),
386        "Delta Correlating Prediction Tables object")
387
388class BOPPrefetcher(QueuedPrefetcher):
389    type = "BOPPrefetcher"
390    cxx_class = "BOPPrefetcher"
391    cxx_header = "mem/cache/prefetch/bop.hh"
392    score_max = Param.Unsigned(31, "Max. score to update the best offset")
393    round_max = Param.Unsigned(100, "Max. round to update the best offset")
394    bad_score = Param.Unsigned(10, "Score at which the HWP is disabled")
395    rr_size = Param.Unsigned(64, "Number of entries of each RR bank")
396    tag_bits = Param.Unsigned(12, "Bits used to store the tag")
397    offset_list_size = Param.Unsigned(46,
398                "Number of entries in the offsets list")
399    negative_offsets_enable = Param.Bool(True,
400                "Initialize the offsets list also with negative values \
401                (i.e. the table will have half of the entries with positive \
402                offsets and the other half with negative ones)")
403    delay_queue_enable = Param.Bool(True, "Enable the delay queue")
404    delay_queue_size = Param.Unsigned(15,
405                "Number of entries in the delay queue")
406    delay_queue_cycles = Param.Cycles(60,
407                "Cycles to delay a write in the left RR table from the delay \
408                queue")
409
410class SBOOEPrefetcher(QueuedPrefetcher):
411    type = 'SBOOEPrefetcher'
412    cxx_class = 'SBOOEPrefetcher'
413    cxx_header = "mem/cache/prefetch/sbooe.hh"
414    latency_buffer_size = Param.Int(32, "Entries in the latency buffer")
415    sequential_prefetchers = Param.Int(9, "Number of sequential prefetchers")
416    sandbox_entries = Param.Int(1024, "Size of the address buffer")
417    score_threshold_pct = Param.Percent(25, "Min. threshold to issue a \
418        prefetch. The value is the percentage of sandbox entries to use")
419
420class STeMSPrefetcher(QueuedPrefetcher):
421    type = "STeMSPrefetcher"
422    cxx_class = "STeMSPrefetcher"
423    cxx_header = "mem/cache/prefetch/spatio_temporal_memory_streaming.hh"
424
425    spatial_region_size = Param.MemorySize("2kB",
426        "Memory covered by a hot zone")
427    active_generation_table_entries = Param.MemorySize("64",
428        "Number of entries in the active generation table")
429    active_generation_table_assoc = Param.Unsigned(64,
430        "Associativity of the active generation table")
431    active_generation_table_indexing_policy = Param.BaseIndexingPolicy(
432        SetAssociative(entry_size = 1,
433            assoc = Parent.active_generation_table_assoc,
434            size = Parent.active_generation_table_entries),
435        "Indexing policy of the active generation table")
436    active_generation_table_replacement_policy = Param.BaseReplacementPolicy(
437        LRURP(), "Replacement policy of the active generation table")
438
439    pattern_sequence_table_entries = Param.MemorySize("16384",
440        "Number of entries in the pattern sequence table")
441    pattern_sequence_table_assoc = Param.Unsigned(16384,
442        "Associativity of the pattern sequence table")
443    pattern_sequence_table_indexing_policy = Param.BaseIndexingPolicy(
444        SetAssociative(entry_size = 1,
445            assoc = Parent.pattern_sequence_table_assoc,
446            size = Parent.pattern_sequence_table_entries),
447        "Indexing policy of the pattern sequence table")
448    pattern_sequence_table_replacement_policy = Param.BaseReplacementPolicy(
449        LRURP(), "Replacement policy of the pattern sequence table")
450
451    region_miss_order_buffer_entries = Param.Unsigned(131072,
452        "Number of entries of the Region Miss Order Buffer")
453    reconstruction_entries = Param.Unsigned(256,
454        "Number of reconstruction entries")
455
456class HWPProbeEventRetiredInsts(HWPProbeEvent):
457    def register(self):
458        if self.obj:
459            for name in self.names:
460                self.prefetcher.getCCObject().addEventProbeRetiredInsts(
461                    self.obj.getCCObject(), name)
462
463class PIFPrefetcher(QueuedPrefetcher):
464    type = 'PIFPrefetcher'
465    cxx_class = 'PIFPrefetcher'
466    cxx_header = "mem/cache/prefetch/pif.hh"
467    cxx_exports = [
468        PyBindMethod("addEventProbeRetiredInsts"),
469    ]
470
471    prec_spatial_region_bits = Param.Unsigned(2,
472        "Number of preceding addresses in the spatial region")
473    succ_spatial_region_bits = Param.Unsigned(8,
474        "Number of subsequent addresses in the spatial region")
475    compactor_entries = Param.Unsigned(2, "Entries in the temp. compactor")
476    stream_address_buffer_entries = Param.Unsigned(7, "Entries in the SAB")
477    history_buffer_size = Param.Unsigned(16, "Entries in the history buffer")
478
479    index_entries = Param.MemorySize("64",
480        "Number of entries in the index")
481    index_assoc = Param.Unsigned(64,
482        "Associativity of the index")
483    index_indexing_policy = Param.BaseIndexingPolicy(
484        SetAssociative(entry_size = 1, assoc = Parent.index_assoc,
485        size = Parent.index_entries),
486        "Indexing policy of the index")
487    index_replacement_policy = Param.BaseReplacementPolicy(LRURP(),
488        "Replacement policy of the index")
489
490    def listenFromProbeRetiredInstructions(self, simObj):
491        if not isinstance(simObj, SimObject):
492            raise TypeError("argument must be of SimObject type")
493        self.addEvent(HWPProbeEventRetiredInsts(self, simObj,"RetiredInstsPC"))
494