PseudoLRUPolicy.cc revision 11030:17240f381d6a
17019SBrad.Beckmann@amd.com/* 27019SBrad.Beckmann@amd.com * Copyright (c) 2013 Advanced Micro Devices, Inc 37019SBrad.Beckmann@amd.com * All rights reserved. 47019SBrad.Beckmann@amd.com * 57019SBrad.Beckmann@amd.com * Redistribution and use in source and binary forms, with or without 67019SBrad.Beckmann@amd.com * modification, are permitted provided that the following conditions are 77019SBrad.Beckmann@amd.com * met: redistributions of source code must retain the above copyright 87019SBrad.Beckmann@amd.com * notice, this list of conditions and the following disclaimer; 97019SBrad.Beckmann@amd.com * redistributions in binary form must reproduce the above copyright 107019SBrad.Beckmann@amd.com * notice, this list of conditions and the following disclaimer in the 117019SBrad.Beckmann@amd.com * documentation and/or other materials provided with the distribution; 127019SBrad.Beckmann@amd.com * neither the name of the copyright holders nor the names of its 137019SBrad.Beckmann@amd.com * contributors may be used to endorse or promote products derived from 147019SBrad.Beckmann@amd.com * this software without specific prior written permission. 157019SBrad.Beckmann@amd.com * 167019SBrad.Beckmann@amd.com * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 177019SBrad.Beckmann@amd.com * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 187019SBrad.Beckmann@amd.com * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 197019SBrad.Beckmann@amd.com * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 207019SBrad.Beckmann@amd.com * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 217019SBrad.Beckmann@amd.com * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 227019SBrad.Beckmann@amd.com * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 237019SBrad.Beckmann@amd.com * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 247019SBrad.Beckmann@amd.com * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 257019SBrad.Beckmann@amd.com * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 267019SBrad.Beckmann@amd.com * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 277019SBrad.Beckmann@amd.com * 287019SBrad.Beckmann@amd.com * Author: Derek Hower 297019SBrad.Beckmann@amd.com */ 306876Ssteve.reinhardt@amd.com 319274Snilay@cs.wisc.edu#include "mem/ruby/structures/PseudoLRUPolicy.hh" 326876Ssteve.reinhardt@amd.com 339274Snilay@cs.wisc.edu 3411021Sjthestness@gmail.com 356876Ssteve.reinhardt@amd.comPseudoLRUPolicy::PseudoLRUPolicy(const Params * p) 366876Ssteve.reinhardt@amd.com : AbstractReplacementPolicy(p) 376876Ssteve.reinhardt@amd.com{ 389338SAndreas.Sandberg@arm.com // associativity cannot exceed capacity of tree representation 398259SBrad.Beckmann@amd.com assert(m_num_sets > 0 && 408259SBrad.Beckmann@amd.com m_assoc > 1 && 418261SBrad.Beckmann@amd.com m_assoc <= (int64_t) sizeof(uint64_t)*4); 428259SBrad.Beckmann@amd.com 4311021Sjthestness@gmail.com m_trees = NULL; 4411021Sjthestness@gmail.com m_num_levels = 0; 4511021Sjthestness@gmail.com 4611021Sjthestness@gmail.com m_effective_assoc = 1; 4711021Sjthestness@gmail.com while (m_effective_assoc < m_assoc) { 4811021Sjthestness@gmail.com // effective associativity is ceiling power of 2 4911021Sjthestness@gmail.com m_effective_assoc <<= 1; 5011021Sjthestness@gmail.com } 5111021Sjthestness@gmail.com int tmp_assoc = m_effective_assoc; 5211021Sjthestness@gmail.com while (true) { 5311021Sjthestness@gmail.com tmp_assoc /= 2; 5411021Sjthestness@gmail.com if(!tmp_assoc) break; 5511021Sjthestness@gmail.com m_num_levels++; 5611021Sjthestness@gmail.com } 5711021Sjthestness@gmail.com assert(m_num_levels < sizeof(unsigned int)*4); 5811021Sjthestness@gmail.com m_trees = new uint64_t[m_num_sets]; 5911663Stushar@ece.gatech.edu for (unsigned i = 0; i < m_num_sets; i++) { 6011663Stushar@ece.gatech.edu m_trees[i] = 0; 6111021Sjthestness@gmail.com } 6211663Stushar@ece.gatech.edu} 6311021Sjthestness@gmail.com 6411021Sjthestness@gmail.comPseudoLRUPolicy * 6511021Sjthestness@gmail.comPseudoLRUReplacementPolicyParams::create() 6611021Sjthestness@gmail.com{ 6711021Sjthestness@gmail.com return new PseudoLRUPolicy(this); 6811021Sjthestness@gmail.com} 6911021Sjthestness@gmail.com 7011021Sjthestness@gmail.com 7111021Sjthestness@gmail.comPseudoLRUPolicy::~PseudoLRUPolicy() 7211021Sjthestness@gmail.com{ 739274Snilay@cs.wisc.edu if (m_trees != NULL) 749274Snilay@cs.wisc.edu delete[] m_trees; 759274Snilay@cs.wisc.edu} 769389Sandreas.hansson@arm.com 779274Snilay@cs.wisc.eduvoid 789274Snilay@cs.wisc.eduPseudoLRUPolicy::touch(int64_t set, int64_t index, Tick time) 7911021Sjthestness@gmail.com{ 80 assert(index >= 0 && index < m_assoc); 81 assert(set >= 0 && set < m_num_sets); 82 83 int tree_index = 0; 84 int node_val; 85 for (int i = m_num_levels - 1; i >= 0; i--) { 86 node_val = (index >> i)&1; 87 if (node_val) 88 m_trees[set] |= node_val << tree_index; 89 else 90 m_trees[set] &= ~(1 << tree_index); 91 tree_index = node_val ? (tree_index*2)+2 : (tree_index*2)+1; 92 } 93 m_last_ref_ptr[set][index] = time; 94} 95 96int64_t 97PseudoLRUPolicy::getVictim(int64_t set) const 98{ 99 int64_t index = 0; 100 101 int tree_index = 0; 102 int node_val; 103 for (unsigned i = 0; i < m_num_levels; i++){ 104 node_val = (m_trees[set] >> tree_index) & 1; 105 index += node_val ? 0 : (m_effective_assoc >> (i + 1)); 106 tree_index = node_val ? (tree_index * 2) + 1 : (tree_index * 2) + 2; 107 } 108 assert(index >= 0 && index < m_effective_assoc); 109 110 /* return either the found index or the max possible index */ 111 /* NOTE: this is not a fair replacement when assoc is not a power of 2 */ 112 return (index > (m_assoc - 1)) ? m_assoc - 1 : index; 113} 114