| /** |
| * 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/brrip_rp.hh" |
| |
| #include "base/random.hh" |
| #include "debug/CacheRepl.hh" |
| |
| BRRIPRP::BRRIPRP(const Params *p) |
| : BaseReplacementPolicy(p), |
| maxRRPV(p->max_RRPV), hitPriority(p->hit_priority), btp(p->btp) |
| { |
| if (maxRRPV == 0){ |
| fatal("max_RRPV should be greater than zero.\n"); |
| } |
| } |
| |
| void |
| BRRIPRP::touch(CacheBlk *blk) |
| { |
| BaseReplacementPolicy::touch(blk); |
| |
| // Update RRPV if not 0 yet |
| // Every hit in HP mode makes the block the last to be evicted, while |
| // in FP mode a hit makes the block less likely to be evicted |
| if (hitPriority) { |
| blk->rrpv = 0; |
| } else if (blk->rrpv > 0) { |
| blk->rrpv--; |
| } |
| } |
| |
| void |
| BRRIPRP::reset(CacheBlk *blk) |
| { |
| BaseReplacementPolicy::reset(blk); |
| |
| // Reset RRPV |
| // Blocks are inserted as "long re-reference" if lower than btp, |
| // "distant re-reference" otherwise |
| if (random_mt.random<unsigned>(1, 100) <= btp) { |
| blk->rrpv = maxRRPV-1; |
| } else { |
| blk->rrpv = maxRRPV; |
| } |
| } |
| |
| CacheBlk* |
| BRRIPRP::getVictim(const ReplacementCandidates& candidates) |
| { |
| // There must be at least one replacement candidate |
| assert(candidates.size() > 0); |
| |
| // Use visitor to search for the victim |
| CacheBlk* blk = candidates[0]; |
| for (const auto& candidate : candidates) { |
| // Stop iteration if found an invalid block |
| if (!candidate->isValid()) { |
| blk = candidate; |
| blk->rrpv = maxRRPV; |
| break; |
| // Update victim block if necessary |
| } else if (candidate->rrpv > blk->rrpv) { |
| blk = candidate; |
| } |
| } |
| |
| // Make sure we don't have an invalid rrpv |
| assert(blk->rrpv <= maxRRPV); |
| |
| // Get difference of block's RRPV to the highest possible RRPV in |
| // order to update the RRPV of all the other blocks accordingly |
| unsigned diff = maxRRPV - blk->rrpv; |
| |
| // No need to update RRPV if there is no difference |
| if (diff > 0){ |
| // Update RRPV of all candidates |
| for (const auto& candidate : candidates) { |
| // Update the block's RPPV with the new value |
| candidate->rrpv += diff; |
| } |
| } |
| |
| DPRINTF(CacheRepl, "set %x, way %x: selecting blk for replacement\n", |
| blk->set, blk->way); |
| |
| return blk; |
| } |
| |
| BRRIPRP* |
| BRRIPRPParams::create() |
| { |
| return new BRRIPRP(this); |
| } |