src/mem/cache/tags/base.hh - public/gem5 - Git at Google

 /*
  * Copyright (c) 2012-2014,2016-2019 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.
  */

 /**
  * @file
  * Declaration of a common base class for cache tagstore objects.
  */

 #ifndef __MEM_CACHE_TAGS_BASE_HH__
 #define __MEM_CACHE_TAGS_BASE_HH__

 #include <cassert>
 #include <cstdint>
 #include <functional>
 #include <string>

 #include "base/callback.hh"
 #include "base/logging.hh"
 #include "base/statistics.hh"
 #include "base/types.hh"
 #include "mem/cache/cache_blk.hh"
 #include "mem/packet.hh"
 #include "params/BaseTags.hh"
 #include "sim/clocked_object.hh"

 class System;
 class IndexingPolicy;
 class ReplaceableEntry;

 /**
  * A common base class of Cache tagstore objects.
  */
 class BaseTags : public ClockedObject
 {
   protected:
     /** The block size of the cache. */
     const unsigned blkSize;
     /** Mask out all bits that aren't part of the block offset. */
     const Addr blkMask;
     /** The size of the cache. */
     const unsigned size;
     /** The tag lookup latency of the cache. */
     const Cycles lookupLatency;

     /** System we are currently operating in. */
     System *system;

     /** Indexing policy */
     BaseIndexingPolicy *indexingPolicy;

     /**
      * The number of tags that need to be touched to meet the warmup
      * percentage.
      */
     const unsigned warmupBound;
     /** Marked true when the cache is warmed up. */
     bool warmedUp;

     /** the number of blocks in the cache */
     const unsigned numBlocks;

     /** The data blocks, 1 per cache block. */
     std::unique_ptr<uint8_t[]> dataBlks;

     /**
      * TODO: It would be good if these stats were acquired after warmup.
      */
     struct BaseTagStats : public Stats::Group
     {
         BaseTagStats(BaseTags &tags);

         void regStats() override;
         void preDumpStats() override;

         BaseTags &tags;

         /** Per cycle average of the number of tags that hold valid data. */
         Stats::Average tagsInUse;

         /** The total number of references to a block before it is replaced. */
         Stats::Scalar totalRefs;

         /**
          * The number of reference counts sampled. This is different
          * from replacements because we sample all the valid blocks
          * when the simulator exits.
          */
         Stats::Scalar sampledRefs;

         /**
          * Average number of references to a block before is was replaced.
          * @todo This should change to an average stat once we have them.
          */
         Stats::Formula avgRefs;

         /** The cycle that the warmup percentage was hit. 0 on failure. */
         Stats::Scalar warmupCycle;

         /** Average occupancy of each requestor using the cache */
         Stats::AverageVector occupancies;

         /** Average occ % of each requestor using the cache */
         Stats::Formula avgOccs;

         /** Occupancy of each context/cpu using the cache */
         Stats::Vector occupanciesTaskId;

         /** Occupancy of each context/cpu using the cache */
         Stats::Vector2d ageTaskId;

         /** Occ % of each context/cpu using the cache */
         Stats::Formula percentOccsTaskId;

         /** Number of tags consulted over all accesses. */
         Stats::Scalar tagAccesses;
         /** Number of data blocks consulted over all accesses. */
         Stats::Scalar dataAccesses;
     } stats;

   public:
     typedef BaseTagsParams Params;
     BaseTags(const Params *p);

     /**
      * Destructor.
      */
     virtual ~BaseTags() {}

     /**
      * Initialize blocks. Must be overriden by every subclass that uses
      * a block type different from its parent's, as the current Python
      * code generation does not allow templates.
      */
     virtual void tagsInit() = 0;

     /**
      * Average in the reference count for valid blocks when the simulation
      * exits.
      */
     void cleanupRefs();

     /**
      * Computes stats just prior to dump event
      */
     void computeStats();

     /**
      * Print all tags used
      */
     std::string print();

     /**
      * Finds the block in the cache without touching it.
      *
      * @param addr The address to look for.
      * @param is_secure True if the target memory space is secure.
      * @return Pointer to the cache block.
      */
     virtual CacheBlk *findBlock(Addr addr, bool is_secure) const;

     /**
      * Find a block given set and way.
      *
      * @param set The set of the block.
      * @param way The way of the block.
      * @return The block.
      */
     virtual ReplaceableEntry* findBlockBySetAndWay(int set, int way) const;

     /**
      * Align an address to the block size.
      * @param addr the address to align.
      * @return The block address.
      */
     Addr blkAlign(Addr addr) const
     {
         return addr & ~blkMask;
     }

     /**
      * Calculate the block offset of an address.
      * @param addr the address to get the offset of.
      * @return the block offset.
      */
     int extractBlkOffset(Addr addr) const
     {
         return (addr & blkMask);
     }

     /**
      * Limit the allocation for the cache ways.
      * @param ways The maximum number of ways available for replacement.
      */
     virtual void setWayAllocationMax(int ways)
     {
         panic("This tag class does not implement way allocation limit!\n");
     }

     /**
      * Get the way allocation mask limit.
      * @return The maximum number of ways available for replacement.
      */
     virtual int getWayAllocationMax() const
     {
         panic("This tag class does not implement way allocation limit!\n");
         return -1;
     }

     /**
      * This function updates the tags when a block is invalidated
      *
      * @param blk A valid block to invalidate.
      */
     virtual void invalidate(CacheBlk *blk)
     {
         assert(blk);
         assert(blk->isValid());

         stats.occupancies[blk->srcRequestorId]--;
         stats.totalRefs += blk->refCount;
         stats.sampledRefs++;

         blk->invalidate();
     }

     /**
      * Find replacement victim based on address. If the address requires
      * blocks to be evicted, their locations are listed for eviction. If a
      * conventional cache is being used, the list only contains the victim.
      * However, if using sector or compressed caches, the victim is one of
      * the blocks to be evicted, but its location is the only one that will
      * be assigned to the newly allocated block associated to this address.
      * @sa insertBlock
      *
      * @param addr Address to find a victim for.
      * @param is_secure True if the target memory space is secure.
      * @param size Size, in bits, of new block to allocate.
      * @param evict_blks Cache blocks to be evicted.
      * @return Cache block to be replaced.
      */
     virtual CacheBlk* findVictim(Addr addr, const bool is_secure,
                                  const std::size_t size,
                                  std::vector<CacheBlk*>& evict_blks) = 0;

     /**
      * Access block and update replacement data. May not succeed, in which case
      * nullptr is returned. This has all the implications of a cache access and
      * should only be used as such. Returns the tag lookup latency as a side
      * effect.
      *
      * @param addr The address to find.
      * @param is_secure True if the target memory space is secure.
      * @param lat The latency of the tag lookup.
      * @return Pointer to the cache block if found.
      */
     virtual CacheBlk* accessBlock(Addr addr, bool is_secure, Cycles &lat) = 0;

     /**
      * Generate the tag from the given address.
      *
      * @param addr The address to get the tag from.
      * @return The tag of the address.
      */
     virtual Addr extractTag(const Addr addr) const;

     /**
      * Insert the new block into the cache and update stats.
      *
      * @param pkt Packet holding the address to update
      * @param blk The block to update.
      */
     virtual void insertBlock(const PacketPtr pkt, CacheBlk *blk);

     /**
      * Regenerate the block address.
      *
      * @param block The block.
      * @return the block address.
      */
     virtual Addr regenerateBlkAddr(const CacheBlk* blk) const = 0;

     /**
      * Visit each block in the tags and apply a visitor
      *
      * The visitor should be a std::function that takes a cache block
      * reference as its parameter.
      *
      * @param visitor Visitor to call on each block.
      */
     virtual void forEachBlk(std::function<void(CacheBlk &)> visitor) = 0;

     /**
      * Find if any of the blocks satisfies a condition
      *
      * The visitor should be a std::function that takes a cache block
      * reference as its parameter. The visitor will terminate the
      * traversal early if the condition is satisfied.
      *
      * @param visitor Visitor to call on each block.
      */
     virtual bool anyBlk(std::function<bool(CacheBlk &)> visitor) = 0;

   private:
     /**
      * Update the reference stats using data from the input block
      *
      * @param blk The input block
      */
     void cleanupRefsVisitor(CacheBlk &blk);

     /**
      * Update the occupancy and age stats using data from the input block
      *
      * @param blk The input block
      */
     void computeStatsVisitor(CacheBlk &blk);
 };

 #endif //__MEM_CACHE_TAGS_BASE_HH__
	/*
	* Copyright (c) 2012-2014,2016-2019 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.
	*/

	/**
	* @file
	* Declaration of a common base class for cache tagstore objects.
	*/

	#ifndef __MEM_CACHE_TAGS_BASE_HH__
	#define __MEM_CACHE_TAGS_BASE_HH__

	#include <cassert>
	#include <cstdint>
	#include <functional>
	#include <string>

	#include "base/callback.hh"
	#include "base/logging.hh"
	#include "base/statistics.hh"
	#include "base/types.hh"
	#include "mem/cache/cache_blk.hh"
	#include "mem/packet.hh"
	#include "params/BaseTags.hh"
	#include "sim/clocked_object.hh"

	class System;
	class IndexingPolicy;
	class ReplaceableEntry;

	/**
	* A common base class of Cache tagstore objects.
	*/
	class BaseTags : public ClockedObject
	{
	protected:
	/** The block size of the cache. */
	const unsigned blkSize;
	/** Mask out all bits that aren't part of the block offset. */
	const Addr blkMask;
	/** The size of the cache. */
	const unsigned size;
	/** The tag lookup latency of the cache. */
	const Cycles lookupLatency;

	/** System we are currently operating in. */
	System *system;

	/** Indexing policy */
	BaseIndexingPolicy *indexingPolicy;

	/**
	* The number of tags that need to be touched to meet the warmup
	* percentage.
	*/
	const unsigned warmupBound;
	/** Marked true when the cache is warmed up. */
	bool warmedUp;

	/** the number of blocks in the cache */
	const unsigned numBlocks;

	/** The data blocks, 1 per cache block. */
	std::unique_ptr<uint8_t[]> dataBlks;

	/**
	* TODO: It would be good if these stats were acquired after warmup.
	*/
	struct BaseTagStats : public Stats::Group
	{
	BaseTagStats(BaseTags &tags);

	void regStats() override;
	void preDumpStats() override;

	BaseTags &tags;

	/** Per cycle average of the number of tags that hold valid data. */
	Stats::Average tagsInUse;

	/** The total number of references to a block before it is replaced. */
	Stats::Scalar totalRefs;

	/**
	* The number of reference counts sampled. This is different
	* from replacements because we sample all the valid blocks
	* when the simulator exits.
	*/
	Stats::Scalar sampledRefs;

	/**
	* Average number of references to a block before is was replaced.
	* @todo This should change to an average stat once we have them.
	*/
	Stats::Formula avgRefs;

	/** The cycle that the warmup percentage was hit. 0 on failure. */
	Stats::Scalar warmupCycle;

	/** Average occupancy of each requestor using the cache */
	Stats::AverageVector occupancies;

	/** Average occ % of each requestor using the cache */
	Stats::Formula avgOccs;

	/** Occupancy of each context/cpu using the cache */
	Stats::Vector occupanciesTaskId;

	/** Occupancy of each context/cpu using the cache */
	Stats::Vector2d ageTaskId;

	/** Occ % of each context/cpu using the cache */
	Stats::Formula percentOccsTaskId;

	/** Number of tags consulted over all accesses. */
	Stats::Scalar tagAccesses;
	/** Number of data blocks consulted over all accesses. */
	Stats::Scalar dataAccesses;
	} stats;

	public:
	typedef BaseTagsParams Params;
	BaseTags(const Params *p);

	/**
	* Destructor.
	*/
	virtual ~BaseTags() {}

	/**
	* Initialize blocks. Must be overriden by every subclass that uses
	* a block type different from its parent's, as the current Python
	* code generation does not allow templates.
	*/
	virtual void tagsInit() = 0;

	/**
	* Average in the reference count for valid blocks when the simulation
	* exits.
	*/
	void cleanupRefs();

	/**
	* Computes stats just prior to dump event
	*/
	void computeStats();

	/**
	* Print all tags used
	*/
	std::string print();

	/**
	* Finds the block in the cache without touching it.
	*
	* @param addr The address to look for.
	* @param is_secure True if the target memory space is secure.
	* @return Pointer to the cache block.
	*/
	virtual CacheBlk *findBlock(Addr addr, bool is_secure) const;

	/**
	* Find a block given set and way.
	*
	* @param set The set of the block.
	* @param way The way of the block.
	* @return The block.
	*/
	virtual ReplaceableEntry* findBlockBySetAndWay(int set, int way) const;

	/**
	* Align an address to the block size.
	* @param addr the address to align.
	* @return The block address.
	*/
	Addr blkAlign(Addr addr) const
	{
	return addr & ~blkMask;
	}

	/**
	* Calculate the block offset of an address.
	* @param addr the address to get the offset of.
	* @return the block offset.
	*/
	int extractBlkOffset(Addr addr) const
	{
	return (addr & blkMask);
	}

	/**
	* Limit the allocation for the cache ways.
	* @param ways The maximum number of ways available for replacement.
	*/
	virtual void setWayAllocationMax(int ways)
	{
	panic("This tag class does not implement way allocation limit!\n");
	}

	/**
	* Get the way allocation mask limit.
	* @return The maximum number of ways available for replacement.
	*/
	virtual int getWayAllocationMax() const
	{
	panic("This tag class does not implement way allocation limit!\n");
	return -1;
	}

	/**
	* This function updates the tags when a block is invalidated
	*
	* @param blk A valid block to invalidate.
	*/
	virtual void invalidate(CacheBlk *blk)
	{
	assert(blk);
	assert(blk->isValid());

	stats.occupancies[blk->srcRequestorId]--;
	stats.totalRefs += blk->refCount;
	stats.sampledRefs++;

	blk->invalidate();
	}

	/**
	* Find replacement victim based on address. If the address requires
	* blocks to be evicted, their locations are listed for eviction. If a
	* conventional cache is being used, the list only contains the victim.
	* However, if using sector or compressed caches, the victim is one of
	* the blocks to be evicted, but its location is the only one that will
	* be assigned to the newly allocated block associated to this address.
	* @sa insertBlock
	*
	* @param addr Address to find a victim for.
	* @param is_secure True if the target memory space is secure.
	* @param size Size, in bits, of new block to allocate.
	* @param evict_blks Cache blocks to be evicted.
	* @return Cache block to be replaced.
	*/
	virtual CacheBlk* findVictim(Addr addr, const bool is_secure,
	const std::size_t size,
	std::vector<CacheBlk*>& evict_blks) = 0;

	/**
	* Access block and update replacement data. May not succeed, in which case
	* nullptr is returned. This has all the implications of a cache access and
	* should only be used as such. Returns the tag lookup latency as a side
	* effect.
	*
	* @param addr The address to find.
	* @param is_secure True if the target memory space is secure.
	* @param lat The latency of the tag lookup.
	* @return Pointer to the cache block if found.
	*/
	virtual CacheBlk* accessBlock(Addr addr, bool is_secure, Cycles &lat) = 0;

	/**
	* Generate the tag from the given address.
	*
	* @param addr The address to get the tag from.
	* @return The tag of the address.
	*/
	virtual Addr extractTag(const Addr addr) const;

	/**
	* Insert the new block into the cache and update stats.
	*
	* @param pkt Packet holding the address to update
	* @param blk The block to update.
	*/
	virtual void insertBlock(const PacketPtr pkt, CacheBlk *blk);

	/**
	* Regenerate the block address.
	*
	* @param block The block.
	* @return the block address.
	*/
	virtual Addr regenerateBlkAddr(const CacheBlk* blk) const = 0;

	/**
	* Visit each block in the tags and apply a visitor
	*
	* The visitor should be a std::function that takes a cache block
	* reference as its parameter.
	*
	* @param visitor Visitor to call on each block.
	*/
	virtual void forEachBlk(std::function<void(CacheBlk &)> visitor) = 0;

	/**
	* Find if any of the blocks satisfies a condition
	*
	* The visitor should be a std::function that takes a cache block
	* reference as its parameter. The visitor will terminate the
	* traversal early if the condition is satisfied.
	*
	* @param visitor Visitor to call on each block.
	*/
	virtual bool anyBlk(std::function<bool(CacheBlk &)> visitor) = 0;

	private:
	/**
	* Update the reference stats using data from the input block
	*
	* @param blk The input block
	*/
	void cleanupRefsVisitor(CacheBlk &blk);

	/**
	* Update the occupancy and age stats using data from the input block
	*
	* @param blk The input block
	*/
	void computeStatsVisitor(CacheBlk &blk);
	};

	#endif //__MEM_CACHE_TAGS_BASE_HH__