weighted_lru_rp.cc

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#include "mem/cache/replacement_policies/weighted_lru_rp.hh"
 
#include <cassert>
 
#include "params/WeightedLRURP.hh"
#include "sim/cur_tick.hh"
 
namespace gem5
{
 
GEM5_DEPRECATED_NAMESPACE(ReplacementPolicy, replacement_policy);
namespace replacement_policy
{
 
WeightedLRU::WeightedLRU(const Params &p)
  : LRU(p)
{
}
 
void
WeightedLRU::touch(const std::shared_ptr<ReplacementData>& replacement_data,
    int occupancy) const
{
    LRU::touch(replacement_data);
    std::static_pointer_cast<WeightedLRUReplData>(replacement_data)->
                                                  last_occ_ptr = occupancy;
}
 
ReplaceableEntry*
WeightedLRU::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->lastTouchTick;
            if (time < victim_replacement_data->lastTouchTick) {
                victim = candidate;
            }
        }
    }
    return victim;
}
 
std::shared_ptr<ReplacementData>
WeightedLRU::instantiateEntry()
{
    return std::shared_ptr<ReplacementData>(new WeightedLRUReplData);
}
 
} // namespace replacement_policy
} // namespace gem5