From: Daniel R. Carvalho Date: Fri, 9 Mar 2018 16:05:39 +0000 (+0100) Subject: mem-cache: Create BRRIP replacement policy X-Git-Tag: v19.0.0.0~2193 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=207cb98c70d753adb1906856fd34a7e288df5318;p=gem5.git mem-cache: Create BRRIP replacement policy Implementation of a Bimodal Re-Reference Interval Prediction replacement policy. Change-Id: I25d4a59a60ef7ac496c66852e394fd6cbaf50912 Reviewed-on: https://gem5-review.googlesource.com/8891 Reviewed-by: Nikos Nikoleris Maintainer: Nikos Nikoleris --- diff --git a/src/mem/cache/blk.hh b/src/mem/cache/blk.hh index a1e45028b..65f32ff91 100644 --- a/src/mem/cache/blk.hh +++ b/src/mem/cache/blk.hh @@ -129,6 +129,11 @@ class CacheBlk */ Tick lastTouchTick; + /** + * Re-Reference Interval Prediction Value. Used with RRIP repl policy. + */ + unsigned rrpv; + protected: /** * Represents that the indicated thread context has a "lock" on diff --git a/src/mem/cache/replacement_policies/ReplacementPolicies.py b/src/mem/cache/replacement_policies/ReplacementPolicies.py index be9f2de50..9176d2b32 100644 --- a/src/mem/cache/replacement_policies/ReplacementPolicies.py +++ b/src/mem/cache/replacement_policies/ReplacementPolicies.py @@ -54,3 +54,13 @@ class RandomRP(BaseReplacementPolicy): type = 'RandomRP' cxx_class = 'RandomRP' cxx_header = "mem/cache/replacement_policies/random_rp.hh" + +class BRRIPRP(BaseReplacementPolicy): + type = 'BRRIPRP' + cxx_class = 'BRRIPRP' + cxx_header = "mem/cache/replacement_policies/brrip_rp.hh" + max_RRPV = Param.Unsigned(3, "Maximum RRPV possible") + hit_priority = Param.Bool(False, + "Prioritize evicting blocks that havent had a hit recently") + btp = Param.Percent(3, + "Percentage of blocks to be inserted with long RRPV") diff --git a/src/mem/cache/replacement_policies/SConscript b/src/mem/cache/replacement_policies/SConscript index 45a7b4f14..4ac8fe8e6 100644 --- a/src/mem/cache/replacement_policies/SConscript +++ b/src/mem/cache/replacement_policies/SConscript @@ -33,6 +33,7 @@ Import('*') SimObject('ReplacementPolicies.py') Source('base.cc') +Source('brrip_rp.cc') Source('fifo_rp.cc') Source('lru_rp.cc') Source('mru_rp.cc') diff --git a/src/mem/cache/replacement_policies/brrip_rp.cc b/src/mem/cache/replacement_policies/brrip_rp.cc new file mode 100644 index 000000000..9185638d7 --- /dev/null +++ b/src/mem/cache/replacement_policies/brrip_rp.cc @@ -0,0 +1,121 @@ +/** + * 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(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); +} diff --git a/src/mem/cache/replacement_policies/brrip_rp.hh b/src/mem/cache/replacement_policies/brrip_rp.hh new file mode 100644 index 000000000..489b81ec0 --- /dev/null +++ b/src/mem/cache/replacement_policies/brrip_rp.hh @@ -0,0 +1,124 @@ +/** + * 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 Re-Reference Interval Prediction replacement policy. + * + * Not-Recently Used (NRU) is an approximation of LRU that uses a single bit + * to determine if a block is going to be re-referenced in the near or distant + * future. + * + * Re-Reference Interval Prediction (RRIP) is an extension of NRU that uses a + * re-reference prediction value to determine if blocks are going to be re- + * used in the near future or not. + * + * The higher the value of the RRPV, the more distant the block is from + * its next access. + * + * Bimodal Re-Reference Interval Prediction (BRRIP) is an extension of RRIP + * that has a probability of not inserting blocks as the LRU. This probability + * is controlled by the bimodal throtle parameter (btp). + * + * From the original paper, this implementation of RRIP is also called + * Static RRIP (SRRIP), as it always inserts blocks with the same RRPV. + */ + +#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_BRRIP_RP_HH__ +#define __MEM_CACHE_REPLACEMENT_POLICIES_BRRIP_RP_HH__ + +#include "mem/cache/replacement_policies/base.hh" +#include "params/BRRIPRP.hh" + +class BRRIPRP : public BaseReplacementPolicy +{ + protected: + /** + * Maximum Re-Reference Prediction Value possible. A block with this + * value as the rrpv has the longest possible re-reference interval, + * that is, it is likely not to be used in the near future, and is + * among the best eviction candidates. + * A maxRRPV of 1 implies in a NRU. + */ + const unsigned maxRRPV; + + /** + * The hit priority (HP) policy replaces blocks that do not receive cache + * hits over any cache block that receives a hit, while the frequency + * priority (FP) policy replaces infrequently re-referenced blocks. + */ + const bool hitPriority; + + /** + * Bimodal throtle parameter. Value in the range [0,100] used to decide + * if a new block is inserted with long or distant re-reference. + */ + const unsigned btp; + + public: + /** Convenience typedef. */ + typedef BRRIPRPParams Params; + + /** + * Construct and initiliaze this replacement policy. + */ + BRRIPRP(const Params *p); + + /** + * Destructor. + */ + ~BRRIPRP() {} + + /** + * Touch a block to update its replacement data. + * + * @param blk Cache block to be touched. + */ + void touch(CacheBlk *blk) override; + + /** + * Reset replacement data for a block. Used when a block is inserted. + * Sets the insertion tick, and update correspondent replacement data. + * Set RRPV according to the insertion policy used. + * + * @param blk Cache block to be reset. + */ + void reset(CacheBlk *blk) override; + + /** + * Find replacement victim using rrpv. + * + * @param cands Replacement candidates, selected by indexing policy. + * @return Cache block to be replaced. + */ + CacheBlk* getVictim(const ReplacementCandidates& candidates) override; +}; + +#endif // __MEM_CACHE_REPLACEMENT_POLICIES_BRRIP_RP_HH__