mem-cache: Create BIP Replacement Policy

Implementation of a Bimodal Insertion Policy replacement policy.

Change-Id: Ife058d0d4310dbcb35858348006189f0b2bf7c37
Reviewed-on: https://gem5-review.googlesource.com/9003
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

src/mem/cache/replacement_policies/ReplacementPolicies.py

@@ -50,6 +50,12 @@ class LRURP(BaseReplacementPolicy):
     cxx_class = 'LRURP'
     cxx_header = "mem/cache/replacement_policies/lru_rp.hh"
 
+class BIPRP(LRURP):
+    type = 'BIPRP'
+    cxx_class = 'BIPRP'
+    cxx_header = "mem/cache/replacement_policies/bip_rp.hh"
+    btp = Param.Percent(3, "Percentage of blocks to be inserted as MRU")
+
 class MRURP(BaseReplacementPolicy):
     type = 'MRURP'
     cxx_class = 'MRURP'

src/mem/cache/replacement_policies/SConscript

@@ -33,6 +33,7 @@ Import('*')
 SimObject('ReplacementPolicies.py')
 
 Source('base.cc')
+Source('bip_rp.cc')
 Source('brrip_rp.cc')
 Source('fifo_rp.cc')
 Source('lfu_rp.cc')

src/mem/cache/replacement_policies/bip_rp.cc

@@ -0,0 +1,59 @@
+/**
+ * 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/bip_rp.hh"
+
+#include "base/random.hh"
+#include "debug/CacheRepl.hh"
+
+BIPRP::BIPRP(const Params *p)
+    : LRURP(p), btp(p->btp)
+{
+}
+
+void
+BIPRP::reset(CacheBlk *blk)
+{
+    BaseReplacementPolicy::reset(blk);
+
+    // Blocks are inserted as MRU if lower than btp, LRU otherwise
+    if (random_mt.random<unsigned>(1, 100) <= btp) {
+        blk->lastTouchTick = curTick();
+    } else {
+        // Make their timestamps as old as possible, so that they become LRU
+        blk->lastTouchTick = 0;
+    }
+}
+
+BIPRP*
+BIPRPParams::create()
+{
+    return new BIPRP(this);
+}

src/mem/cache/replacement_policies/bip_rp.hh

@@ -0,0 +1,84 @@
+/**
+ * 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 Bimodal Interval Prediction replacement policy.
+ * Has a probability of when placing new blocks, placing them as MRU.
+ *
+ * Although both LRU and LIP can be seen as specific cases of BIP
+ * where the bimodal throtle parameter are 1 and 0, respectively, we
+ * decide not to inherit from it, and do the other way around (inherit
+ * from LRU) for efficiency reasons.
+ *
+ * In the original paper they use btp = 1/32 ~= 3%.
+ */
+
+#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_LIP_RP_HH__
+#define __MEM_CACHE_REPLACEMENT_POLICIES_LIP_RP_HH__
+
+#include "mem/cache/replacement_policies/lru_rp.hh"
+#include "params/BIPRP.hh"
+
+class BIPRP : public LRURP
+{
+  protected:
+    /**
+     * Bimodal throtle parameter. Value in the range [0,100] used to decide
+     * if a new block is inserted at the MRU or LRU position.
+     */
+    const unsigned btp;
+
+  public:
+    /** Convenience typedef. */
+    typedef BIPRPParams Params;
+
+    /**
+     * Construct and initiliaze this replacement policy.
+     */
+    BIPRP(const Params *p);
+
+    /**
+     * Destructor.
+     */
+    ~BIPRP() {}
+
+    /**
+     * Reset replacement data for a block. Used when a block is inserted.
+     * Sets the insertion tick, and update correspondent replacement data.
+     * Uses the bimodal throtle parameter to decide whether the new block
+     * should be inserted as MRU, or LRU.
+     *
+     * @param blk Cache block to be reset.
+     */
+    void reset(CacheBlk *blk) override;
+};
+
+#endif // __MEM_CACHE_REPLACEMENT_POLICIES_LIP_RP_HH__