irregular_stream_buffer.hh revision 13669
1/** 2 * Copyright (c) 2018 Metempsy Technology Consulting 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are 7 * met: redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer; 9 * redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution; 12 * neither the name of the copyright holders nor the names of its 13 * contributors may be used to endorse or promote products derived from 14 * this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * Authors: Javier Bueno 29 */ 30 31/** 32 * Implementation of the Irregular Stream Buffer prefetcher 33 * Reference: 34 * Jain, A., & Lin, C. (2013, December). Linearizing irregular memory 35 * accesses for improved correlated prefetching. In Proceedings of the 36 * 46th Annual IEEE/ACM International Symposium on Microarchitecture 37 * (pp. 247-259). ACM. 38 */ 39 40#ifndef __MEM_CACHE_PREFETCH_IRREGULAR_STREAM_BUFFER_HH__ 41#define __MEM_CACHE_PREFETCH_IRREGULAR_STREAM_BUFFER_HH__ 42 43#include "base/callback.hh" 44#include "mem/cache/prefetch/associative_set.hh" 45#include "mem/cache/prefetch/queued.hh" 46 47struct IrregularStreamBufferPrefetcherParams; 48 49class IrregularStreamBufferPrefetcher : public QueuedPrefetcher 50{ 51 /** Maximum value of the confidence counters */ 52 const unsigned maxCounterValue; 53 /** Size in bytes of a temporal stream */ 54 const size_t chunkSize; 55 /** Number of prefetch candidates per Physical-to-Structural entry */ 56 const unsigned prefetchCandidatesPerEntry; 57 /** Number of maximum prefetches requests created when predicting */ 58 const unsigned degree; 59 60 /** 61 * Training Unit Entry datatype, it holds the last accessed address and 62 * its secure flag 63 */ 64 struct TrainingUnitEntry : public TaggedEntry { 65 Addr lastAddress; 66 bool lastAddressSecure; 67 }; 68 /** Map of PCs to Training unit entries */ 69 AssociativeSet<TrainingUnitEntry> trainingUnit; 70 71 /** Address Mapping entry, holds an address and a confidence counter */ 72 struct AddressMapping { 73 Addr address; 74 unsigned counter; 75 AddressMapping() : address(0), counter(0) 76 {} 77 }; 78 79 /** 80 * Maps a set of contiguous addresses to another set of (not necessarily 81 * contiguos) addresses, with their corresponding confidence counters 82 */ 83 struct AddressMappingEntry : public TaggedEntry { 84 std::vector<AddressMapping> mappings; 85 AddressMappingEntry(size_t num_mappings) : mappings(num_mappings) 86 {} 87 void reset() override 88 { 89 for (auto &entry : mappings) { 90 entry.address = 0; 91 entry.counter = 0; 92 } 93 } 94 }; 95 96 /** Physical-to-Structured mappings table */ 97 AssociativeSet<AddressMappingEntry> psAddressMappingCache; 98 /** Structured-to-Physical mappings table */ 99 AssociativeSet<AddressMappingEntry> spAddressMappingCache; 100 /** 101 * Counter of allocated structural addresses, increased by "chunkSize", 102 * each time a new structured address is allocated 103 */ 104 uint64_t structuralAddressCounter; 105 106 /** 107 * Add a mapping to the Structured-to-Physica mapping table 108 * @param structuralAddress structural address 109 * @param is_secure whether this page is inside the secure memory area 110 * @param physical_address corresponding physical address 111 */ 112 void addStructuralToPhysicalEntry(Addr structuralAddress, bool is_secure, 113 Addr physical_address); 114 115 /** 116 * Obtain the Physical-to-Structured mapping entry of the given physical 117 * address. If the entry does not exist a new one is allocated, replacing 118 * an existing one if needed. 119 * @param paddr physical address 120 * @param is_secure whether this page is inside the secure memory area 121 * @result reference to the entry 122 */ 123 AddressMapping& getPSMapping(Addr paddr, bool is_secure); 124 public: 125 IrregularStreamBufferPrefetcher( 126 const IrregularStreamBufferPrefetcherParams *p); 127 ~IrregularStreamBufferPrefetcher() {} 128 void calculatePrefetch(const PrefetchInfo &pfi, 129 std::vector<AddrPriority> &addresses) override; 130}; 131#endif//__MEM_CACHE_PREFETCH_IRREGULAR_STREAM_BUFFER_HH__ 132