--- /dev/null
+/**
+ * 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.
+ *
+ * Authors: Daniel Carvalho
+ */
+
+#include "mem/cache/replacement_policies/second_chance_rp.hh"
+
+SecondChanceRP::SecondChanceRP(const Params *p)
+ : FIFORP(p)
+{
+}
+
+void
+SecondChanceRP::useSecondChance(
+ const std::shared_ptr<SecondChanceReplData>& replacement_data) const
+{
+ // Reset FIFO data
+ FIFORP::reset(replacement_data);
+
+ // Use second chance
+ replacement_data->hasSecondChance = false;
+}
+
+void
+SecondChanceRP::invalidate(
+ const std::shared_ptr<ReplacementData>& replacement_data) const
+{
+ FIFORP::invalidate(replacement_data);
+
+ // Do not give a second chance to invalid entries
+ std::static_pointer_cast<SecondChanceReplData>(
+ replacement_data)->hasSecondChance = false;
+}
+
+void
+SecondChanceRP::touch(const std::shared_ptr<ReplacementData>& replacement_data) const
+{
+ FIFORP::touch(replacement_data);
+
+ // Whenever an entry is touched, it is given a second chance
+ std::static_pointer_cast<SecondChanceReplData>(
+ replacement_data)->hasSecondChance = true;
+}
+
+void
+SecondChanceRP::reset(const std::shared_ptr<ReplacementData>& replacement_data) const
+{
+ FIFORP::reset(replacement_data);
+
+ // Entries are inserted with a second chance
+ std::static_pointer_cast<SecondChanceReplData>(
+ replacement_data)->hasSecondChance = true;
+}
+
+ReplaceableEntry*
+SecondChanceRP::getVictim(const ReplacementCandidates& candidates) const
+{
+ // There must be at least one replacement candidate
+ assert(candidates.size() > 0);
+
+ // Search for invalid entries, as they have the eviction priority
+ for (const auto& candidate : candidates) {
+ // Cast candidate's replacement data
+ std::shared_ptr<SecondChanceReplData> candidate_replacement_data =
+ std::static_pointer_cast<SecondChanceReplData>(
+ candidate->replacementData);
+
+ // Stop iteration if found an invalid entry
+ if ((candidate_replacement_data->tickInserted == Tick(0)) &&
+ !candidate_replacement_data->hasSecondChance) {
+ return candidate;
+ }
+ }
+
+ // Visit all candidates to find victim
+ ReplaceableEntry* victim = candidates[0];
+ bool search_victim = true;
+ while (search_victim) {
+ // Do a FIFO victim search
+ victim = FIFORP::getVictim(candidates);
+
+ // Cast victim's replacement data for code readability
+ std::shared_ptr<SecondChanceReplData> victim_replacement_data =
+ std::static_pointer_cast<SecondChanceReplData>(
+ victim->replacementData);
+
+ // If victim has a second chance, use it and repeat search
+ if (victim_replacement_data->hasSecondChance) {
+ useSecondChance(victim_replacement_data);
+ } else {
+ // Found victim
+ search_victim = false;
+ }
+ }
+
+ return victim;
+}
+
+std::shared_ptr<ReplacementData>
+SecondChanceRP::instantiateEntry()
+{
+ return std::shared_ptr<ReplacementData>(new SecondChanceReplData());
+}
+
+SecondChanceRP*
+SecondChanceRPParams::create()
+{
+ return new SecondChanceRP(this);
+}
--- /dev/null
+/**
+ * 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.
+ *
+ * Authors: Daniel Carvalho
+ */
+
+/**
+ * @file
+ * Declaration of a Second-Chance replacement policy.
+ * The victim is chosen using the timestamp. The oldest entry is chosen
+ * to be evicted, if it hasn't been touched since its insertion. If it
+ * has been touched, it is given a second chance and re-inserted at the
+ * end of the queue.
+ */
+
+#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_SECOND_CHANCE_RP_HH__
+#define __MEM_CACHE_REPLACEMENT_POLICIES_SECOND_CHANCE_RP_HH__
+
+#include "mem/cache/replacement_policies/fifo_rp.hh"
+#include "params/SecondChanceRP.hh"
+
+class SecondChanceRP : public FIFORP
+{
+ protected:
+ /** Second-Chance-specific implementation of replacement data. */
+ struct SecondChanceReplData : public FIFOReplData
+ {
+ /**
+ * This is different from isTouched because isTouched accounts only
+ * for insertion, while this bit is reset every new re-insertion.
+ * @sa SecondChanceRP.
+ */
+ bool hasSecondChance;
+
+ /**
+ * Default constructor.
+ */
+ SecondChanceReplData() : FIFOReplData(), hasSecondChance(false) {}
+ };
+
+ /**
+ * Use replacement data's second chance.
+ *
+ * @param replacement_data Entry that will use its second chance.
+ */
+ void useSecondChance(
+ const std::shared_ptr<SecondChanceReplData>& replacement_data) const;
+
+ public:
+ /** Convenience typedef. */
+ typedef SecondChanceRPParams Params;
+
+ /**
+ * Construct and initiliaze this replacement policy.
+ */
+ SecondChanceRP(const Params *p);
+
+ /**
+ * Destructor.
+ */
+ ~SecondChanceRP() {}
+
+ /**
+ * Invalidate replacement data to set it as the next probable victim.
+ * Invalid entries do not have a second chance, and their last touch tick
+ * is set as the oldest possible.
+ *
+ * @param replacement_data Replacement data to be invalidated.
+ */
+ void invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
+ const override;
+
+ /**
+ * Touch an entry to update its re-insertion tick and second chance bit.
+ *
+ * @param replacement_data Replacement data to be touched.
+ */
+ void touch(const std::shared_ptr<ReplacementData>& replacement_data) const
+ override;
+
+ /**
+ * Reset replacement data. Used when an entry is inserted or re-inserted
+ * in the queue.
+ * Sets its insertion tick and second chance bit.
+ *
+ * @param replacement_data Replacement data to be reset.
+ */
+ void reset(const std::shared_ptr<ReplacementData>& replacement_data) const
+ override;
+
+ /**
+ * Find replacement victim using insertion timestamps and second chance
+ * bit.
+ *
+ * @param cands Replacement candidates, selected by indexing policy.
+ * @return Replacement entry to be replaced.
+ */
+ ReplaceableEntry* getVictim(const ReplacementCandidates& candidates) const
+ override;
+
+ /**
+ * Instantiate a replacement data entry.
+ *
+ * @return A shared pointer to the new replacement data.
+ */
+ std::shared_ptr<ReplacementData> instantiateEntry() override;
+};
+
+#endif // __MEM_CACHE_REPLACEMENT_POLICIES_SECOND_CHANCE_RP_HH__
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