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/**
* Copyright (c) 2018 Inria
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* 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;
* neither the name of the copyright holders 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
* OWNER 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.
*/
#include "mem/cache/replacement_policies/random_rp.hh"
#include <cassert>
#include <memory>
#include "base/random.hh"
#include "params/RandomRP.hh"
RandomRP::RandomRP(const Params *p)
: BaseReplacementPolicy(p)
{
}
void
RandomRP::invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
const
{
// Unprioritize replacement data victimization
std::static_pointer_cast<RandomReplData>(
replacement_data)->valid = false;
}
void
RandomRP::touch(const std::shared_ptr<ReplacementData>& replacement_data) const
{
}
void
RandomRP::reset(const std::shared_ptr<ReplacementData>& replacement_data) const
{
// Unprioritize replacement data victimization
std::static_pointer_cast<RandomReplData>(
replacement_data)->valid = true;
}
ReplaceableEntry*
RandomRP::getVictim(const ReplacementCandidates& candidates) const
{
// There must be at least one replacement candidate
assert(candidates.size() > 0);
// Choose one candidate at random
ReplaceableEntry* victim = candidates[random_mt.random<unsigned>(0,
candidates.size() - 1)];
// Visit all candidates to search for an invalid entry. If one is found,
// its eviction is prioritized
for (const auto& candidate : candidates) {
if (!std::static_pointer_cast<RandomReplData>(
candidate->replacementData)->valid) {
victim = candidate;
break;
}
}
return victim;
}
std::shared_ptr<ReplacementData>
RandomRP::instantiateEntry()
{
return std::shared_ptr<ReplacementData>(new RandomReplData());
}
RandomRP*
RandomRPParams::create()
{
return new RandomRP(this);
}