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authorDaniel R. Carvalho <odanrc@yahoo.com.br>2018-03-09 17:05:39 +0100
committerDaniel Carvalho <odanrc@yahoo.com.br>2018-03-30 16:46:59 +0000
commit207cb98c70d753adb1906856fd34a7e288df5318 (patch)
tree14605bebba99c52891ec210e1f8b8c4a2278912d /src
parentab46e32b36810bec329a015d794f0aafff8d4b6f (diff)
downloadgem5-207cb98c70d753adb1906856fd34a7e288df5318.tar.xz
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 <nikos.nikoleris@arm.com> Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Diffstat (limited to 'src')
-rw-r--r--src/mem/cache/blk.hh5
-rw-r--r--src/mem/cache/replacement_policies/ReplacementPolicies.py10
-rw-r--r--src/mem/cache/replacement_policies/SConscript1
-rw-r--r--src/mem/cache/replacement_policies/brrip_rp.cc121
-rw-r--r--src/mem/cache/replacement_policies/brrip_rp.hh124
5 files changed, 261 insertions, 0 deletions
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<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);
+}
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__