src/mem/cache/tags/fa_lru.cc - testing/jenkins-gem5-prod - Git at Google

 /*
  * Copyright (c) 2018 Inria
  * Copyright (c) 2013,2016-2018 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 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
  *          Nikos Nikoleris
  *          Daniel Carvalho
  */

 /**
  * @file
  * Definitions a fully associative LRU tagstore.
  */

 #include "mem/cache/tags/fa_lru.hh"

 #include <cassert>
 #include <sstream>

 #include "base/intmath.hh"
 #include "base/logging.hh"
 #include "mem/cache/base.hh"
 #include "mem/cache/replacement_policies/replaceable_entry.hh"

 std::string
 FALRUBlk::print() const
 {
     return csprintf("%s inCachesMask: %#x", CacheBlk::print(), inCachesMask);
 }

 FALRU::FALRU(const Params *p)
     : BaseTags(p),

       cacheTracking(p->min_tracked_cache_size, size, blkSize)
 {
     if (!isPowerOf2(blkSize))
         fatal("cache block size (in bytes) `%d' must be a power of two",
               blkSize);
     if (!isPowerOf2(size))
         fatal("Cache Size must be power of 2 for now");

     blks = new FALRUBlk[numBlocks];
 }

 FALRU::~FALRU()
 {
     delete[] blks;
 }

 void
 FALRU::tagsInit()
 {
     head = &(blks[0]);
     head->prev = nullptr;
     head->next = &(blks[1]);
     head->setPosition(0, 0);
     head->data = &dataBlks[0];

     for (unsigned i = 1; i < numBlocks - 1; i++) {
         blks[i].prev = &(blks[i-1]);
         blks[i].next = &(blks[i+1]);
         blks[i].setPosition(0, i);

         // Associate a data chunk to the block
         blks[i].data = &dataBlks[blkSize*i];
     }

     tail = &(blks[numBlocks - 1]);
     tail->prev = &(blks[numBlocks - 2]);
     tail->next = nullptr;
     tail->setPosition(0, numBlocks - 1);
     tail->data = &dataBlks[(numBlocks - 1) * blkSize];

     cacheTracking.init(head, tail);
 }

 void
 FALRU::regStats()
 {
     BaseTags::regStats();
     cacheTracking.regStats(name());
 }

 void
 FALRU::invalidate(CacheBlk *blk)
 {
     // Erase block entry reference in the hash table
     auto num_erased M5_VAR_USED =
         tagHash.erase(std::make_pair(blk->tag, blk->isSecure()));

     // Sanity check; only one block reference should be erased
     assert(num_erased == 1);

     // Invalidate block entry. Must be done after the hash is erased
     BaseTags::invalidate(blk);

     // Decrease the number of tags in use
     tagsInUse--;

     // Move the block to the tail to make it the next victim
     moveToTail((FALRUBlk*)blk);
 }

 CacheBlk*
 FALRU::accessBlock(Addr addr, bool is_secure, Cycles &lat)
 {
     return accessBlock(addr, is_secure, lat, 0);
 }

 CacheBlk*
 FALRU::accessBlock(Addr addr, bool is_secure, Cycles &lat,
                    CachesMask *in_caches_mask)
 {
     CachesMask mask = 0;
     FALRUBlk* blk = static_cast<FALRUBlk*>(findBlock(addr, is_secure));

     // If a cache hit
     if (blk && blk->isValid()) {
         mask = blk->inCachesMask;

         moveToHead(blk);
     }

     if (in_caches_mask) {
         *in_caches_mask = mask;
     }

     cacheTracking.recordAccess(blk);

     // The tag lookup latency is the same for a hit or a miss
     lat = lookupLatency;

     return blk;
 }

 CacheBlk*
 FALRU::findBlock(Addr addr, bool is_secure) const
 {
     FALRUBlk* blk = nullptr;

     Addr tag = extractTag(addr);
     auto iter = tagHash.find(std::make_pair(tag, is_secure));
     if (iter != tagHash.end()) {
         blk = (*iter).second;
     }

     if (blk && blk->isValid()) {
         assert(blk->tag == tag);
         assert(blk->isSecure() == is_secure);
     }

     return blk;
 }

 ReplaceableEntry*
 FALRU::findBlockBySetAndWay(int set, int way) const
 {
     assert(set == 0);
     return &blks[way];
 }

 CacheBlk*
 FALRU::findVictim(Addr addr, const bool is_secure,
                   std::vector<CacheBlk*>& evict_blks) const
 {
     // The victim is always stored on the tail for the FALRU
     FALRUBlk* victim = tail;

     // There is only one eviction for this replacement
     evict_blks.push_back(victim);

     return victim;
 }

 void
 FALRU::insertBlock(const PacketPtr pkt, CacheBlk *blk)
 {
     FALRUBlk* falruBlk = static_cast<FALRUBlk*>(blk);

     // Make sure block is not present in the cache
     assert(falruBlk->inCachesMask == 0);

     // Do common block insertion functionality
     BaseTags::insertBlock(pkt, blk);

     // Increment tag counter
     tagsInUse++;

     // New block is the MRU
     moveToHead(falruBlk);

     // Insert new block in the hash table
     tagHash[std::make_pair(blk->tag, blk->isSecure())] = falruBlk;
 }

 void
 FALRU::moveToHead(FALRUBlk *blk)
 {
     // If block is not already head, do the moving
     if (blk != head) {
         cacheTracking.moveBlockToHead(blk);
         // If block is tail, set previous block as new tail
         if (blk == tail){
             assert(blk->next == nullptr);
             tail = blk->prev;
             tail->next = nullptr;
         // Inform block's surrounding blocks that it has been moved
         } else {
             blk->prev->next = blk->next;
             blk->next->prev = blk->prev;
         }

         // Swap pointers
         blk->next = head;
         blk->prev = nullptr;
         head->prev = blk;
         head = blk;

         cacheTracking.check(head, tail);
     }
 }

 void
 FALRU::moveToTail(FALRUBlk *blk)
 {
     // If block is not already tail, do the moving
     if (blk != tail) {
         cacheTracking.moveBlockToTail(blk);
         // If block is head, set next block as new head
         if (blk == head){
             assert(blk->prev == nullptr);
             head = blk->next;
             head->prev = nullptr;
         // Inform block's surrounding blocks that it has been moved
         } else {
             blk->prev->next = blk->next;
             blk->next->prev = blk->prev;
         }

         // Swap pointers
         blk->prev = tail;
         blk->next = nullptr;
         tail->next = blk;
         tail = blk;

         cacheTracking.check(head, tail);
     }
 }

 FALRU *
 FALRUParams::create()
 {
     return new FALRU(this);
 }

 void
 FALRU::CacheTracking::check(const FALRUBlk *head, const FALRUBlk *tail) const
 {
 #ifdef FALRU_DEBUG
     const FALRUBlk* blk = head;
     unsigned curr_size = 0;
     unsigned tracked_cache_size = minTrackedSize;
     CachesMask in_caches_mask = inAllCachesMask;
     int j = 0;

     while (blk) {
         panic_if(blk->inCachesMask != in_caches_mask, "Expected cache mask "
                  "%x found %x", blk->inCachesMask, in_caches_mask);

         curr_size += blkSize;
         if (curr_size == tracked_cache_size && blk != tail) {
             panic_if(boundaries[j] != blk, "Unexpected boundary for the %d-th "
                      "cache", j);
             tracked_cache_size <<= 1;
             // from this point, blocks fit only in the larger caches
             in_caches_mask &= ~(1U << j);
             ++j;
         }
         blk = blk->next;
     }
 #endif // FALRU_DEBUG
 }

 void
 FALRU::CacheTracking::init(FALRUBlk *head, FALRUBlk *tail)
 {
     // early exit if we are not tracking any extra caches
     FALRUBlk* blk = numTrackedCaches ? head : nullptr;
     unsigned curr_size = 0;
     unsigned tracked_cache_size = minTrackedSize;
     CachesMask in_caches_mask = inAllCachesMask;
     int j = 0;

     while (blk) {
         blk->inCachesMask = in_caches_mask;

         curr_size += blkSize;
         if (curr_size == tracked_cache_size && blk != tail) {
             boundaries[j] = blk;

             tracked_cache_size <<= 1;
             // from this point, blocks fit only in the larger caches
             in_caches_mask &= ~(1U << j);
             ++j;
         }
         blk = blk->next;
     }
 }


 void
 FALRU::CacheTracking::moveBlockToHead(FALRUBlk *blk)
 {
     // Get the mask of all caches, in which the block didn't fit
     // before moving it to the head
     CachesMask update_caches_mask = inAllCachesMask ^ blk->inCachesMask;

     for (int i = 0; i < numTrackedCaches; i++) {
         CachesMask current_cache_mask = 1U << i;
         if (current_cache_mask & update_caches_mask) {
             // if the ith cache didn't fit the block (before it is moved to
             // the head), move the ith boundary 1 block closer to the
             // MRU
             boundaries[i]->inCachesMask &= ~current_cache_mask;
             boundaries[i] = boundaries[i]->prev;
         } else if (boundaries[i] == blk) {
             // Make sure the boundary doesn't point to the block
             // we are about to move
             boundaries[i] = blk->prev;
         }
     }

     // Make block reside in all caches
     blk->inCachesMask = inAllCachesMask;
 }

 void
 FALRU::CacheTracking::moveBlockToTail(FALRUBlk *blk)
 {
     CachesMask update_caches_mask = blk->inCachesMask;

     for (int i = 0; i < numTrackedCaches; i++) {
         CachesMask current_cache_mask = 1U << i;
         if (current_cache_mask & update_caches_mask) {
             // if the ith cache fitted the block (before it is moved to
             // the tail), move the ith boundary 1 block closer to the
             // LRU
             boundaries[i] = boundaries[i]->next;
             if (boundaries[i] == blk) {
                 // Make sure the boundary doesn't point to the block
                 // we are about to move
                 boundaries[i] = blk->next;
             }
             boundaries[i]->inCachesMask |= current_cache_mask;
         }
     }

     // The block now fits only in the actual cache
     blk->inCachesMask = 0;
 }

 void
 FALRU::CacheTracking::recordAccess(FALRUBlk *blk)
 {
     for (int i = 0; i < numTrackedCaches; i++) {
         if (blk && ((1U << i) & blk->inCachesMask)) {
             hits[i]++;
         } else {
             misses[i]++;
         }
     }

     // Record stats for the actual cache too
     if (blk && blk->isValid()) {
         hits[numTrackedCaches]++;
     } else {
         misses[numTrackedCaches]++;
     }

     accesses++;
 }

 void
 printSize(std::ostream &stream, size_t size)
 {
     static const char *SIZES[] = { "B", "kB", "MB", "GB", "TB", "ZB" };
     int div = 0;
     while (size >= 1024 && div < (sizeof SIZES / sizeof *SIZES)) {
         div++;
         size >>= 10;
     }
     stream << size << SIZES[div];
 }

 void
 FALRU::CacheTracking::regStats(std::string name)
 {
     hits
         .init(numTrackedCaches + 1)
         .name(name + ".falru_hits")
         .desc("The number of hits in each cache size.")
         ;
     misses
         .init(numTrackedCaches + 1)
         .name(name + ".falru_misses")
         .desc("The number of misses in each cache size.")
         ;
     accesses
         .name(name + ".falru_accesses")
         .desc("The number of accesses to the FA LRU cache.")
         ;

     for (unsigned i = 0; i < numTrackedCaches + 1; ++i) {
         std::stringstream size_str;
         printSize(size_str, minTrackedSize << i);
         hits.subname(i, size_str.str());
         hits.subdesc(i, "Hits in a " + size_str.str() + " cache");
         misses.subname(i, size_str.str());
         misses.subdesc(i, "Misses in a " + size_str.str() + " cache");
     }
 }
	/*
	* Copyright (c) 2018 Inria
	* Copyright (c) 2013,2016-2018 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 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
	* Nikos Nikoleris
	* Daniel Carvalho
	*/

	/**
	* @file
	* Definitions a fully associative LRU tagstore.
	*/

	#include "mem/cache/tags/fa_lru.hh"

	#include <cassert>
	#include <sstream>

	#include "base/intmath.hh"
	#include "base/logging.hh"
	#include "mem/cache/base.hh"
	#include "mem/cache/replacement_policies/replaceable_entry.hh"

	std::string
	FALRUBlk::print() const
	{
	return csprintf("%s inCachesMask: %#x", CacheBlk::print(), inCachesMask);
	}

	FALRU::FALRU(const Params *p)
	: BaseTags(p),

	cacheTracking(p->min_tracked_cache_size, size, blkSize)
	{
	if (!isPowerOf2(blkSize))
	fatal("cache block size (in bytes) `%d' must be a power of two",
	blkSize);
	if (!isPowerOf2(size))
	fatal("Cache Size must be power of 2 for now");

	blks = new FALRUBlk[numBlocks];
	}

	FALRU::~FALRU()
	{
	delete[] blks;
	}

	void
	FALRU::tagsInit()
	{
	head = &(blks[0]);
	head->prev = nullptr;
	head->next = &(blks[1]);
	head->setPosition(0, 0);
	head->data = &dataBlks[0];

	for (unsigned i = 1; i < numBlocks - 1; i++) {
	blks[i].prev = &(blks[i-1]);
	blks[i].next = &(blks[i+1]);
	blks[i].setPosition(0, i);

	// Associate a data chunk to the block
	blks[i].data = &dataBlks[blkSize*i];
	}

	tail = &(blks[numBlocks - 1]);
	tail->prev = &(blks[numBlocks - 2]);
	tail->next = nullptr;
	tail->setPosition(0, numBlocks - 1);
	tail->data = &dataBlks[(numBlocks - 1) * blkSize];

	cacheTracking.init(head, tail);
	}

	void
	FALRU::regStats()
	{
	BaseTags::regStats();
	cacheTracking.regStats(name());
	}

	void
	FALRU::invalidate(CacheBlk *blk)
	{
	// Erase block entry reference in the hash table
	auto num_erased M5_VAR_USED =
	tagHash.erase(std::make_pair(blk->tag, blk->isSecure()));

	// Sanity check; only one block reference should be erased
	assert(num_erased == 1);

	// Invalidate block entry. Must be done after the hash is erased
	BaseTags::invalidate(blk);

	// Decrease the number of tags in use
	tagsInUse--;

	// Move the block to the tail to make it the next victim
	moveToTail((FALRUBlk*)blk);
	}

	CacheBlk*
	FALRU::accessBlock(Addr addr, bool is_secure, Cycles &lat)
	{
	return accessBlock(addr, is_secure, lat, 0);
	}

	CacheBlk*
	FALRU::accessBlock(Addr addr, bool is_secure, Cycles &lat,
	CachesMask *in_caches_mask)
	{
	CachesMask mask = 0;
	FALRUBlk* blk = static_cast<FALRUBlk*>(findBlock(addr, is_secure));

	// If a cache hit
	if (blk && blk->isValid()) {
	mask = blk->inCachesMask;

	moveToHead(blk);
	}

	if (in_caches_mask) {
	*in_caches_mask = mask;
	}

	cacheTracking.recordAccess(blk);

	// The tag lookup latency is the same for a hit or a miss
	lat = lookupLatency;

	return blk;
	}

	CacheBlk*
	FALRU::findBlock(Addr addr, bool is_secure) const
	{
	FALRUBlk* blk = nullptr;

	Addr tag = extractTag(addr);
	auto iter = tagHash.find(std::make_pair(tag, is_secure));
	if (iter != tagHash.end()) {
	blk = (*iter).second;
	}

	if (blk && blk->isValid()) {
	assert(blk->tag == tag);
	assert(blk->isSecure() == is_secure);
	}

	return blk;
	}

	ReplaceableEntry*
	FALRU::findBlockBySetAndWay(int set, int way) const
	{
	assert(set == 0);
	return &blks[way];
	}

	CacheBlk*
	FALRU::findVictim(Addr addr, const bool is_secure,
	std::vector<CacheBlk*>& evict_blks) const
	{
	// The victim is always stored on the tail for the FALRU
	FALRUBlk* victim = tail;

	// There is only one eviction for this replacement
	evict_blks.push_back(victim);

	return victim;
	}

	void
	FALRU::insertBlock(const PacketPtr pkt, CacheBlk *blk)
	{
	FALRUBlk* falruBlk = static_cast<FALRUBlk*>(blk);

	// Make sure block is not present in the cache
	assert(falruBlk->inCachesMask == 0);

	// Do common block insertion functionality
	BaseTags::insertBlock(pkt, blk);

	// Increment tag counter
	tagsInUse++;

	// New block is the MRU
	moveToHead(falruBlk);

	// Insert new block in the hash table
	tagHash[std::make_pair(blk->tag, blk->isSecure())] = falruBlk;
	}

	void
	FALRU::moveToHead(FALRUBlk *blk)
	{
	// If block is not already head, do the moving
	if (blk != head) {
	cacheTracking.moveBlockToHead(blk);
	// If block is tail, set previous block as new tail
	if (blk == tail){
	assert(blk->next == nullptr);
	tail = blk->prev;
	tail->next = nullptr;
	// Inform block's surrounding blocks that it has been moved
	} else {
	blk->prev->next = blk->next;
	blk->next->prev = blk->prev;
	}

	// Swap pointers
	blk->next = head;
	blk->prev = nullptr;
	head->prev = blk;
	head = blk;

	cacheTracking.check(head, tail);
	}
	}

	void
	FALRU::moveToTail(FALRUBlk *blk)
	{
	// If block is not already tail, do the moving
	if (blk != tail) {
	cacheTracking.moveBlockToTail(blk);
	// If block is head, set next block as new head
	if (blk == head){
	assert(blk->prev == nullptr);
	head = blk->next;
	head->prev = nullptr;
	// Inform block's surrounding blocks that it has been moved
	} else {
	blk->prev->next = blk->next;
	blk->next->prev = blk->prev;
	}

	// Swap pointers
	blk->prev = tail;
	blk->next = nullptr;
	tail->next = blk;
	tail = blk;

	cacheTracking.check(head, tail);
	}
	}

	FALRU *
	FALRUParams::create()
	{
	return new FALRU(this);
	}

	void
	FALRU::CacheTracking::check(const FALRUBlk head, const FALRUBlk tail) const
	{
	#ifdef FALRU_DEBUG
	const FALRUBlk* blk = head;
	unsigned curr_size = 0;
	unsigned tracked_cache_size = minTrackedSize;
	CachesMask in_caches_mask = inAllCachesMask;
	int j = 0;

	while (blk) {
	panic_if(blk->inCachesMask != in_caches_mask, "Expected cache mask "
	"%x found %x", blk->inCachesMask, in_caches_mask);

	curr_size += blkSize;
	if (curr_size == tracked_cache_size && blk != tail) {
	panic_if(boundaries[j] != blk, "Unexpected boundary for the %d-th "
	"cache", j);
	tracked_cache_size <<= 1;
	// from this point, blocks fit only in the larger caches
	in_caches_mask &= ~(1U << j);
	++j;
	}
	blk = blk->next;
	}
	#endif // FALRU_DEBUG
	}

	void
	FALRU::CacheTracking::init(FALRUBlk head, FALRUBlk tail)
	{
	// early exit if we are not tracking any extra caches
	FALRUBlk* blk = numTrackedCaches ? head : nullptr;
	unsigned curr_size = 0;
	unsigned tracked_cache_size = minTrackedSize;
	CachesMask in_caches_mask = inAllCachesMask;
	int j = 0;

	while (blk) {
	blk->inCachesMask = in_caches_mask;

	curr_size += blkSize;
	if (curr_size == tracked_cache_size && blk != tail) {
	boundaries[j] = blk;

	tracked_cache_size <<= 1;
	// from this point, blocks fit only in the larger caches
	in_caches_mask &= ~(1U << j);
	++j;
	}
	blk = blk->next;
	}
	}


	void
	FALRU::CacheTracking::moveBlockToHead(FALRUBlk *blk)
	{
	// Get the mask of all caches, in which the block didn't fit
	// before moving it to the head
	CachesMask update_caches_mask = inAllCachesMask ^ blk->inCachesMask;

	for (int i = 0; i < numTrackedCaches; i++) {
	CachesMask current_cache_mask = 1U << i;
	if (current_cache_mask & update_caches_mask) {
	// if the ith cache didn't fit the block (before it is moved to
	// the head), move the ith boundary 1 block closer to the
	// MRU
	boundaries[i]->inCachesMask &= ~current_cache_mask;
	boundaries[i] = boundaries[i]->prev;
	} else if (boundaries[i] == blk) {
	// Make sure the boundary doesn't point to the block
	// we are about to move
	boundaries[i] = blk->prev;
	}
	}

	// Make block reside in all caches
	blk->inCachesMask = inAllCachesMask;
	}

	void
	FALRU::CacheTracking::moveBlockToTail(FALRUBlk *blk)
	{
	CachesMask update_caches_mask = blk->inCachesMask;

	for (int i = 0; i < numTrackedCaches; i++) {
	CachesMask current_cache_mask = 1U << i;
	if (current_cache_mask & update_caches_mask) {
	// if the ith cache fitted the block (before it is moved to
	// the tail), move the ith boundary 1 block closer to the
	// LRU
	boundaries[i] = boundaries[i]->next;
	if (boundaries[i] == blk) {
	// Make sure the boundary doesn't point to the block
	// we are about to move
	boundaries[i] = blk->next;
	}
	boundaries[i]->inCachesMask \|= current_cache_mask;
	}
	}

	// The block now fits only in the actual cache
	blk->inCachesMask = 0;
	}

	void
	FALRU::CacheTracking::recordAccess(FALRUBlk *blk)
	{
	for (int i = 0; i < numTrackedCaches; i++) {
	if (blk && ((1U << i) & blk->inCachesMask)) {
	hits[i]++;
	} else {
	misses[i]++;
	}
	}

	// Record stats for the actual cache too
	if (blk && blk->isValid()) {
	hits[numTrackedCaches]++;
	} else {
	misses[numTrackedCaches]++;
	}

	accesses++;
	}

	void
	printSize(std::ostream &stream, size_t size)
	{
	static const char *SIZES[] = { "B", "kB", "MB", "GB", "TB", "ZB" };
	int div = 0;
	while (size >= 1024 && div < (sizeof SIZES / sizeof *SIZES)) {
	div++;
	size >>= 10;
	}
	stream << size << SIZES[div];
	}

	void
	FALRU::CacheTracking::regStats(std::string name)
	{
	hits
	.init(numTrackedCaches + 1)
	.name(name + ".falru_hits")
	.desc("The number of hits in each cache size.")
	;
	misses
	.init(numTrackedCaches + 1)
	.name(name + ".falru_misses")
	.desc("The number of misses in each cache size.")
	;
	accesses
	.name(name + ".falru_accesses")
	.desc("The number of accesses to the FA LRU cache.")
	;

	for (unsigned i = 0; i < numTrackedCaches + 1; ++i) {
	std::stringstream size_str;
	printSize(size_str, minTrackedSize << i);
	hits.subname(i, size_str.str());
	hits.subdesc(i, "Hits in a " + size_str.str() + " cache");
	misses.subname(i, size_str.str());
	misses.subdesc(i, "Misses in a " + size_str.str() + " cache");
	}
	}