/*
* Copyright (c) 1999-2012 Mark D. Hill and David A. Wood
* 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_PREFETCHER_HH__
#define __MEM_RUBY_STRUCTURES_PREFETCHER_HH__
// Implements Power 4 like prefetching
#include <bitset>
#include "base/statistics.hh"
#include "mem/ruby/common/Address.hh"
#include "mem/ruby/network/MessageBuffer.hh"
#include "mem/ruby/slicc_interface/AbstractController.hh"
#include "mem/ruby/slicc_interface/RubyRequest.hh"
#include "mem/ruby/system/RubySystem.hh"
#include "params/Prefetcher.hh"
#include "sim/sim_object.hh"
#include "sim/system.hh"
#define MAX_PF_INFLIGHT 8
class PrefetchEntry
{
public:
/// constructor
PrefetchEntry()
{
// default: 1 cache-line stride
m_stride = (1 << RubySystem::getBlockSizeBits());
m_use_time = Cycles(0);
m_is_valid = false;
}
//! The base address for the stream prefetch
Addr m_address;
//! stride distance to get next address from
int m_stride;
//! the last time that any prefetched request was used
Cycles m_use_time;
//! valid bit for each stream
bool m_is_valid;
//! L1D prefetches loads and stores
RubyRequestType m_type;
//! Bitset for tracking prefetches for which addresses have been
//! issued, which ones have completed.
std::bitset<MAX_PF_INFLIGHT> requestIssued;
std::bitset<MAX_PF_INFLIGHT> requestCompleted;
};
class Prefetcher : public SimObject
{
public:
typedef PrefetcherParams Params;
Prefetcher(const Params *p);
~Prefetcher();
void issueNextPrefetch(Addr address, PrefetchEntry *stream);
/**
* Implement the prefetch hit(miss) callback interface.
* These functions are called by the cache when it hits(misses)
* on a line with the line's prefetch bit set. If this address
* hits in m_array we will continue prefetching the stream.
*/
void observePfHit(Addr address);
void observePfMiss(Addr address);
/**
* Observe a memory miss from the cache.
*
* @param address The physical address that missed out of the cache.
*/
void observeMiss(Addr address, const RubyRequestType& type);
/**
* Print out some statistics
*/
void print(std::ostream& out) const;
void setController(AbstractController *_ctrl)
{ m_controller = _ctrl; }
void regStats();
private:
/**
* Returns an unused stream buffer (or if all are used, returns the
* least recently used (accessed) stream buffer).
* @return The index of the least recently used stream buffer.
*/
uint32_t getLRUindex(void);
//! clear a non-unit stride prefetcher entry
void clearNonunitEntry(uint32_t index);
//! allocate a new stream buffer at a specific index
void initializeStream(Addr address, int stride,
uint32_t index, const RubyRequestType& type);
//! get pointer to the matching stream entry, returns NULL if not found
//! index holds the multiple of the stride this address is.
PrefetchEntry* getPrefetchEntry(Addr address,
uint32_t &index);
/// access a unit stride filter to determine if there is a hit
bool accessUnitFilter(std::vector<Addr>& filter_table,
uint32_t *hit_table, uint32_t &index, Addr address,
int stride, bool &alloc);
/// access a unit stride filter to determine if there is a hit
bool accessNonunitFilter(Addr address, int *stride,
bool &alloc);
/// determine the page aligned address
Addr pageAddress(Addr addr) const;
//! number of prefetch streams available
uint32_t m_num_streams;
//! an array of the active prefetch streams
std::vector<PrefetchEntry> m_array;
//! number of misses I must see before allocating a stream
uint32_t m_train_misses;
//! number of initial prefetches to startup a stream
uint32_t m_num_startup_pfs;
//! number of stride filters
uint32_t m_num_unit_filters;
//! number of non-stride filters
uint32_t m_num_nonunit_filters;
/// a unit stride filter array: helps reduce BW requirement of
/// prefetching
std::vector<Addr> m_unit_filter;
/// a round robin pointer into the unit filter group
uint32_t m_unit_filter_index;
//! An array used to count the of times particular filter entries
//! have been hit
uint32_t *m_unit_filter_hit;
//! a negative nit stride filter array: helps reduce BW requirement
//! of prefetching
std::vector<Addr> m_negative_filter;
/// a round robin pointer into the negative filter group
uint32_t m_negative_filter_index;
/// An array used to count the of times particular filter entries
/// have been hit
uint32_t *m_negative_filter_hit;
/// a non-unit stride filter array: helps reduce BW requirement of
/// prefetching
std::vector<Addr> m_nonunit_filter;
/// An array of strides (in # of cache lines) for the filter entries
int *m_nonunit_stride;
/// An array used to count the of times particular filter entries
/// have been hit
uint32_t *m_nonunit_hit;
/// a round robin pointer into the unit filter group
uint32_t m_nonunit_index;
/// Used for allowing prefetches across pages.
bool m_prefetch_cross_pages;
AbstractController *m_controller;
const Addr m_page_shift;
//! Count of accesses to the prefetcher
Stats::Scalar numMissObserved;
//! Count of prefetch streams allocated
Stats::Scalar numAllocatedStreams;
//! Count of prefetch requests made
Stats::Scalar numPrefetchRequested;
//! Count of prefetch requests accepted
Stats::Scalar numPrefetchAccepted;
//! Count of prefetches dropped
Stats::Scalar numDroppedPrefetches;
//! Count of successful prefetches
Stats::Scalar numHits;
//! Count of partial successful prefetches
Stats::Scalar numPartialHits;
//! Count of pages crossed
Stats::Scalar numPagesCrossed;
//! Count of misses incurred for blocks that were prefetched
Stats::Scalar numMissedPrefetchedBlocks;
};
#endif // __MEM_RUBY_STRUCTURES_PREFETCHER_HH__