src/mem/ruby/system/WeightedLRUPolicy.cc

/*
 * Copyright (c) 2013-2015 Advanced Micro Devices, Inc.
 * All rights reserved.
 *
 * For use for simulation and test purposes only
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * Author: Derek Hower
 */

#include "mem/ruby/system/WeightedLRUPolicy.hh"

WeightedLRUPolicy::WeightedLRUPolicy(const Params* p)
    : AbstractReplacementPolicy(p), m_cache(p->cache)
{
    m_last_occ_ptr = new int*[m_num_sets];
    for (unsigned i = 0; i < m_num_sets; i++){
        m_last_occ_ptr[i] = new int[m_assoc];
        for (unsigned j = 0; j < m_assoc; j++){
            m_last_occ_ptr[i][j] = 0;
        }
    }
}

WeightedLRUPolicy *
WeightedLRUReplacementPolicyParams::create()
{
    return new WeightedLRUPolicy(this);
}

WeightedLRUPolicy::~WeightedLRUPolicy()
{
    if (m_last_occ_ptr != NULL){
        for (unsigned i = 0; i < m_num_sets; i++){
            if (m_last_occ_ptr[i] != NULL){
                delete[] m_last_occ_ptr[i];
            }
        }
        delete[] m_last_occ_ptr;
    }
}

void
WeightedLRUPolicy::touch(int64_t set, int64_t index, Tick time)
{
    assert(index >= 0 && index < m_assoc);
    assert(set >= 0 && set < m_num_sets);

    m_last_ref_ptr[set][index] = time;
}

void
WeightedLRUPolicy::touch(int64_t set, int64_t index, Tick time, int occupancy)
{
    assert(index >= 0 && index < m_assoc);
    assert(set >= 0 && set < m_num_sets);

    m_last_ref_ptr[set][index] = time;
    m_last_occ_ptr[set][index] = occupancy;
}

int64_t
WeightedLRUPolicy::getVictim(int64_t set) const
{
    Tick time, smallest_time;
    int64_t smallest_index;

    smallest_index = 0;
    smallest_time = m_last_ref_ptr[set][0];
    int smallest_weight = m_last_ref_ptr[set][0];

    for (unsigned i = 1; i < m_assoc; i++) {

        int weight = m_last_occ_ptr[set][i];
        if (weight < smallest_weight) {
            smallest_weight = weight;
            smallest_index = i;
            smallest_time = m_last_ref_ptr[set][i];
        } else if (weight == smallest_weight) {
            time = m_last_ref_ptr[set][i];
            if (time < smallest_time) {
                smallest_index = i;
                smallest_time = time;
            }
        }
    }
    return smallest_index;
}