changeset c00b5ba43967 in /z/repo/gem5
details: http://repo.gem5.org/gem5?cmd=changeset;node=c00b5ba43967
description:
mem: refactor LRU cache tags and add random replacement tags
this patch implements a new tags class that uses a random replacement
policy.
these tags prefer to evict invalid blocks first, if none are available a
replacement candidate is chosen at random.
this patch factors out the common code in the LRU class and creates a
new
abstract class: the BaseSetAssoc class. any set associative tag class
must
implement the functionality related to the actual replacement policy in
the
following methods:
accessBlock()
findVictim()
insertBlock()
invalidate()
diffstat:
src/mem/cache/base.cc | 3 +
src/mem/cache/cache.cc | 2 +
src/mem/cache/tags/SConscript | 4 +-
src/mem/cache/tags/Tags.py | 18 +-
src/mem/cache/tags/base_set_assoc.cc | 203 +++++++++++++++++
src/mem/cache/tags/base_set_assoc.hh | 396 +++++++++++++++++++++++++++++++++++
src/mem/cache/tags/lru.cc | 258 +---------------------
src/mem/cache/tags/lru.hh | 226 +-------------------
src/mem/cache/tags/random_repl.cc | 89 +++++++
src/mem/cache/tags/random_repl.hh | 68 ++++++
10 files changed, 806 insertions(+), 461 deletions(-)
diffs (truncated from 1438 to 300 lines):
diff -r f3e9fe1600d6 -r c00b5ba43967 src/mem/cache/base.cc
--- a/src/mem/cache/base.cc Mon Jul 28 12:22:00 2014 -0400
+++ b/src/mem/cache/base.cc Mon Jul 28 12:23:23 2014 -0400
@@ -49,6 +49,7 @@
#include "debug/Drain.hh"
#include "mem/cache/tags/fa_lru.hh"
#include "mem/cache/tags/lru.hh"
+#include "mem/cache/tags/random_repl.hh"
#include "mem/cache/base.hh"
#include "mem/cache/cache.hh"
#include "mem/cache/mshr.hh"
@@ -783,6 +784,8 @@
if (numSets == 1)
warn("Consider using FALRU tags for a fully associative cache\n");
return new Cache<LRU>(this);
+ } else if (dynamic_cast<RandomRepl*>(tags)) {
+ return new Cache<RandomRepl>(this);
} else {
fatal("No suitable tags selected\n");
}
diff -r f3e9fe1600d6 -r c00b5ba43967 src/mem/cache/cache.cc
--- a/src/mem/cache/cache.cc Mon Jul 28 12:22:00 2014 -0400
+++ b/src/mem/cache/cache.cc Mon Jul 28 12:23:23 2014 -0400
@@ -38,6 +38,7 @@
#include "mem/cache/tags/fa_lru.hh"
#include "mem/cache/tags/lru.hh"
+#include "mem/cache/tags/random_repl.hh"
#include "mem/cache/cache_impl.hh"
// Template Instantiations
@@ -45,5 +46,6 @@
template class Cache<FALRU>;
template class Cache<LRU>;
+template class Cache<RandomRepl>;
#endif //DOXYGEN_SHOULD_SKIP_THIS
diff -r f3e9fe1600d6 -r c00b5ba43967 src/mem/cache/tags/SConscript
--- a/src/mem/cache/tags/SConscript Mon Jul 28 12:22:00 2014 -0400
+++ b/src/mem/cache/tags/SConscript Mon Jul 28 12:23:23 2014 -0400
@@ -33,5 +33,7 @@
SimObject('Tags.py')
Source('base.cc')
+Source('base_set_assoc.cc')
+Source('lru.cc')
+Source('random_repl.cc')
Source('fa_lru.cc')
-Source('lru.cc')
diff -r f3e9fe1600d6 -r c00b5ba43967 src/mem/cache/tags/Tags.py
--- a/src/mem/cache/tags/Tags.py Mon Jul 28 12:22:00 2014 -0400
+++ b/src/mem/cache/tags/Tags.py Mon Jul 28 12:23:23 2014 -0400
@@ -53,13 +53,23 @@
hit_latency = Param.Cycles(Parent.hit_latency,
"The hit latency for this cache")
-class LRU(BaseTags):
+class BaseSetAssoc(BaseTags):
+ type = 'BaseSetAssoc'
+ abstract = True
+ cxx_header = "mem/cache/tags/base_set_assoc.hh"
+ assoc = Param.Int(Parent.assoc, "associativity")
+ sequential_access = Param.Bool(Parent.sequential_access,
+ "Whether to access tags and data sequentially")
+
+class LRU(BaseSetAssoc):
type = 'LRU'
cxx_class = 'LRU'
cxx_header = "mem/cache/tags/lru.hh"
- assoc = Param.Int(Parent.assoc, "associativity")
- sequential_access = Param.Bool(Parent.sequential_access,
- "Whether to access tags and data sequentially")
+
+class RandomRepl(BaseSetAssoc):
+ type = 'RandomRepl'
+ cxx_class = 'RandomRepl'
+ cxx_header = "mem/cache/tags/random_repl.hh"
class FALRU(BaseTags):
type = 'FALRU'
diff -r f3e9fe1600d6 -r c00b5ba43967 src/mem/cache/tags/base_set_assoc.cc
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/mem/cache/tags/base_set_assoc.cc Mon Jul 28 12:23:23 2014 -0400
@@ -0,0 +1,203 @@
+/*
+ * Copyright (c) 2012-2013 ARM Limited
+ * All rights reserved.
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder. You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Copyright (c) 2003-2005,2014 The Regents of The University of Michigan
+ * 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: Erik Hallnor
+ */
+
+/**
+ * @file
+ * Definitions of a base set associative tag store.
+ */
+
+#include <string>
+
+#include "base/intmath.hh"
+#include "mem/cache/tags/base_set_assoc.hh"
+#include "sim/core.hh"
+
+using namespace std;
+
+BaseSetAssoc::BaseSetAssoc(const Params *p)
+ :BaseTags(p), assoc(p->assoc),
+ numSets(p->size / (p->block_size * p->assoc)),
+ sequentialAccess(p->sequential_access)
+{
+ // Check parameters
+ if (blkSize < 4 || !isPowerOf2(blkSize)) {
+ fatal("Block size must be at least 4 and a power of 2");
+ }
+ if (numSets <= 0 || !isPowerOf2(numSets)) {
+ fatal("# of sets must be non-zero and a power of 2");
+ }
+ if (assoc <= 0) {
+ fatal("associativity must be greater than zero");
+ }
+ if (hitLatency <= 0) {
+ fatal("access latency must be greater than zero");
+ }
+
+ blkMask = blkSize - 1;
+ setShift = floorLog2(blkSize);
+ setMask = numSets - 1;
+ tagShift = setShift + floorLog2(numSets);
+ warmedUp = false;
+ /** @todo Make warmup percentage a parameter. */
+ warmupBound = numSets * assoc;
+
+ sets = new SetType[numSets];
+ blks = new BlkType[numSets * assoc];
+ // allocate data storage in one big chunk
+ numBlocks = numSets * assoc;
+ dataBlks = new uint8_t[numBlocks * blkSize];
+
+ unsigned blkIndex = 0; // index into blks array
+ for (unsigned i = 0; i < numSets; ++i) {
+ sets[i].assoc = assoc;
+
+ sets[i].blks = new BlkType*[assoc];
+
+ // link in the data blocks
+ for (unsigned j = 0; j < assoc; ++j) {
+ // locate next cache block
+ BlkType *blk = &blks[blkIndex];
+ blk->data = &dataBlks[blkSize*blkIndex];
+ ++blkIndex;
+
+ // invalidate new cache block
+ blk->invalidate();
+
+ //EGH Fix Me : do we need to initialize blk?
+
+ // Setting the tag to j is just to prevent long chains in the hash
+ // table; won't matter because the block is invalid
+ blk->tag = j;
+ blk->whenReady = 0;
+ blk->isTouched = false;
+ blk->size = blkSize;
+ sets[i].blks[j]=blk;
+ blk->set = i;
+ }
+ }
+}
+
+BaseSetAssoc::~BaseSetAssoc()
+{
+ delete [] dataBlks;
+ delete [] blks;
+ delete [] sets;
+}
+
+BaseSetAssoc::BlkType*
+BaseSetAssoc::findBlock(Addr addr, bool is_secure) const
+{
+ Addr tag = extractTag(addr);
+ unsigned set = extractSet(addr);
+ BlkType *blk = sets[set].findBlk(tag, is_secure);
+ return blk;
+}
+
+void
+BaseSetAssoc::clearLocks()
+{
+ for (int i = 0; i < numBlocks; i++){
+ blks[i].clearLoadLocks();
+ }
+}
+
+std::string
+BaseSetAssoc::print() const {
+ std::string cache_state;
+ for (unsigned i = 0; i < numSets; ++i) {
+ // link in the data blocks
+ for (unsigned j = 0; j < assoc; ++j) {
+ BlkType *blk = sets[i].blks[j];
+ if (blk->isValid())
+ cache_state += csprintf("\tset: %d block: %d %s\n", i, j,
+ blk->print());
+ }
+ }
+ if (cache_state.empty())
+ cache_state = "no valid tags\n";
+ return cache_state;
+}
+
+void
+BaseSetAssoc::cleanupRefs()
+{
+ for (unsigned i = 0; i < numSets*assoc; ++i) {
+ if (blks[i].isValid()) {
+ totalRefs += blks[i].refCount;
+ ++sampledRefs;
+ }
+ }
+}
+
+void
+BaseSetAssoc::computeStats()
+{
+ for (unsigned i = 0; i < ContextSwitchTaskId::NumTaskId; ++i) {
+ occupanciesTaskId[i] = 0;
+ for (unsigned j = 0; j < 5; ++j) {
+ ageTaskId[i][j] = 0;
+ }
+ }
+
+ for (unsigned i = 0; i < numSets * assoc; ++i) {
+ if (blks[i].isValid()) {
+ assert(blks[i].task_id < ContextSwitchTaskId::NumTaskId);
+ occupanciesTaskId[blks[i].task_id]++;
+ Tick age = curTick() - blks[i].tickInserted;
+ assert(age >= 0);
+
+ int age_index;
+ if (age / SimClock::Int::us < 10) { // <10us
+ age_index = 0;
+ } else if (age / SimClock::Int::us < 100) { // <100us
+ age_index = 1;
+ } else if (age / SimClock::Int::ms < 1) { // <1ms
+ age_index = 2;
+ } else if (age / SimClock::Int::ms < 10) { // <10ms
+ age_index = 3;
+ } else
+ age_index = 4; // >10ms
+
+ ageTaskId[blks[i].task_id][age_index]++;
+ }
+ }
+}
diff -r f3e9fe1600d6 -r c00b5ba43967 src/mem/cache/tags/base_set_assoc.hh
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/mem/cache/tags/base_set_assoc.hh Mon Jul 28 12:23:23 2014 -0400
@@ -0,0 +1,396 @@
+/*
+ * Copyright (c) 2012-2013 ARM Limited
+ * All rights reserved.
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
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