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/*
* 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.
*
* Authors: Derek Hower
*/
#include "mem/ruby/system/WeightedLRUPolicy.hh"
#include <cassert>
#include <memory>
WeightedLRUPolicy::WeightedLRUPolicy(const Params* p)
: BaseReplacementPolicy(p)
{
}
WeightedLRUPolicy *
WeightedLRUReplacementPolicyParams::create()
{
return new WeightedLRUPolicy(this);
}
void
WeightedLRUPolicy::touch(const std::shared_ptr<ReplacementData>&
replacement_data) const
{
std::static_pointer_cast<WeightedLRUReplData>(replacement_data)->
last_touch_tick = curTick();
}
void
WeightedLRUPolicy::touch(const std::shared_ptr<ReplacementData>&
replacement_data, int occupancy) const
{
std::static_pointer_cast<WeightedLRUReplData>(replacement_data)->
last_touch_tick = curTick();
std::static_pointer_cast<WeightedLRUReplData>(replacement_data)->
last_occ_ptr = occupancy;
}
ReplaceableEntry*
WeightedLRUPolicy::getVictim(const ReplacementCandidates& candidates) const
{
assert(candidates.size() > 0);
ReplaceableEntry* victim = candidates[0];
// Use weight (last_occ_ptr) to find victim.
// Evict the block that has the smallest weight.
// If two blocks have the same weight, evict the oldest one.
for (const auto& candidate : candidates) {
// candidate's replacement_data
std::shared_ptr<WeightedLRUReplData> candidate_replacement_data =
std::static_pointer_cast<WeightedLRUReplData>(
candidate->replacementData);
// victim's replacement_data
std::shared_ptr<WeightedLRUReplData> victim_replacement_data =
std::static_pointer_cast<WeightedLRUReplData>(
victim->replacementData);
if (candidate_replacement_data->last_occ_ptr <
victim_replacement_data->last_occ_ptr) {
victim = candidate;
} else if (candidate_replacement_data->last_occ_ptr ==
victim_replacement_data->last_occ_ptr) {
// Evict the block with a smaller tick.
Tick time = candidate_replacement_data->last_touch_tick;
if (time < victim_replacement_data->last_touch_tick) {
victim = candidate;
}
}
}
return victim;
}
std::shared_ptr<ReplacementData>
WeightedLRUPolicy::instantiateEntry()
{
return std::shared_ptr<ReplacementData>(new WeightedLRUReplData);
}
void
WeightedLRUPolicy::reset(const std::shared_ptr<ReplacementData>&
replacement_data) const
{
// Set last touch timestamp
std::static_pointer_cast<WeightedLRUReplData>(
replacement_data)->last_touch_tick = curTick();
}
void
WeightedLRUPolicy::invalidate(const std::shared_ptr<ReplacementData>&
replacement_data) const
{
// Reset last touch timestamp
std::static_pointer_cast<WeightedLRUReplData>(
replacement_data)->last_touch_tick = Tick(0);
}
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