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/*
* Copyright (c) 2007 Mark D. Hill and David A. Wood
* Copyright (c) 2013 Advanced Micro Devices, Inc
* 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.
*/
#ifndef __MEM_RUBY_STRUCTURES_PSEUDOLRUPOLICY_HH__
#define __MEM_RUBY_STRUCTURES_PSEUDOLRUPOLICY_HH__
#include "mem/ruby/structures/AbstractReplacementPolicy.hh"
#include "params/PseudoLRUReplacementPolicy.hh"
/**
* Implementation of tree-based pseudo-LRU replacement
*
* Works for any associativity between 1 and 128.
*
* Also implements associativities that are not a power of 2 by
* ignoring paths that lead to a larger index (i.e. truncating the
* tree). Note that when this occurs, the algorithm becomes less
* fair, as it will favor indicies in the larger (by index) half of
* the associative set. This is most unfair when the nearest power of
* 2 is one below the associativy, and most fair when it is one above.
*/
class PseudoLRUPolicy : public AbstractReplacementPolicy
{
public:
typedef PseudoLRUReplacementPolicyParams Params;
PseudoLRUPolicy(const Params * p);
~PseudoLRUPolicy();
void touch(int64 set, int64 way, Tick time);
int64 getVictim(int64 set) const;
private:
unsigned int m_effective_assoc; /** nearest (to ceiling) power of 2 */
unsigned int m_num_levels; /** number of levels in the tree */
uint64* m_trees; /** bit representation of the
* trees, one for each set */
};
#endif // __MEM_RUBY_STRUCTURES_PSEUDOLRUPOLICY_HH__
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