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Diffstat (limited to 'src/mem/cache/miss/mshr_queue.hh')
| -rw-r--r-- | src/mem/cache/miss/mshr_queue.hh | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/src/mem/cache/miss/mshr_queue.hh b/src/mem/cache/miss/mshr_queue.hh new file mode 100644 index 000000000..3e1d3f39f --- /dev/null +++ b/src/mem/cache/miss/mshr_queue.hh @@ -0,0 +1,239 @@ +/* + * 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 + */ + +/** @file + * Declaration of a structure to manage MSHRs. + */ + +#ifndef __MSHR_QUEUE_HH__ +#define __MSHR_QUEUE_HH__ + +#include <vector> +#include "mem/cache/miss/mshr.hh" + +/** + * A Class for maintaining a list of pending and allocated memory requests. + */ +class MSHRQueue { + private: + /** MSHR storage. */ + MSHR* registers; + /** Holds pointers to all allocated MSHRs. */ + MSHR::List allocatedList; + /** Holds pointers to MSHRs that haven't been sent to the bus. */ + MSHR::List pendingList; + /** Holds non allocated MSHRs. */ + MSHR::List freeList; + + // Parameters + /** + * The total number of MSHRs in this queue. This number is set as the + * number of MSHRs requested plus (numReserve - 1). This allows for + * the same number of effective MSHRs while still maintaining the reserve. + */ + const int numMSHRs; + + /** + * The number of MSHRs to hold in reserve. This is needed because copy + * operations can allocate upto 4 MSHRs at one time. + */ + const int numReserve; + + public: + /** The number of allocated MSHRs. */ + int allocated; + /** The number of MSHRs that have been forwarded to the bus. */ + int inServiceMSHRs; + /** The number of targets waiting for response. */ + int allocatedTargets; + + /** + * Create a queue with a given number of MSHRs. + * @param num_mshrs The number of MSHRs in this queue. + * @param reserve The minimum number of MSHRs needed to satisfy any access. + */ + MSHRQueue(int num_mshrs, int reserve = 1); + + /** Destructor */ + ~MSHRQueue(); + + /** + * Find the first MSHR that matches the provide address and asid. + * @param addr The address to find. + * @param asid The address space id. + * @return Pointer to the matching MSHR, null if not found. + */ + MSHR* findMatch(Addr addr, int asid) const; + + /** + * Find and return all the matching MSHRs in the provided vector. + * @param addr The address to find. + * @param asid The address space ID. + * @param matches The vector to return pointers to the matching MSHRs. + * @return True if any matches are found, false otherwise. + * @todo Typedef the vector?? + */ + bool findMatches(Addr addr, int asid, std::vector<MSHR*>& matches) const; + + /** + * Find any pending requests that overlap the given request. + * @param req The request to find. + * @return A pointer to the earliest matching MSHR. + */ + MSHR* findPending(Packet * &pkt) const; + + /** + * Allocates a new MSHR for the request and size. This places the request + * as the first target in the MSHR. + * @param req The request to handle. + * @param size The number in bytes to fetch from memory. + * @return The a pointer to the MSHR allocated. + * + * @pre There are free MSHRs. + */ + MSHR* allocate(Packet * &pkt, int size = 0); + + /** + * Allocate a read request for the given address, and places the given + * target on the target list. + * @param addr The address to fetch. + * @param asid The address space for the fetch. + * @param size The number of bytes to request. + * @param target The first target for the request. + * @return Pointer to the new MSHR. + */ + MSHR* allocateFetch(Addr addr, int asid, int size, Packet * &target); + + /** + * Allocate a target list for the given address. + * @param addr The address to fetch. + * @param asid The address space for the fetch. + * @param size The number of bytes to request. + * @return Pointer to the new MSHR. + */ + MSHR* allocateTargetList(Addr addr, int asid, int size); + + /** + * Removes the given MSHR from the queue. This places the MSHR on the + * free list. + * @param mshr + */ + void deallocate(MSHR* mshr); + + /** + * Allocates a target to the given MSHR. Used to keep track of the number + * of outstanding targets. + * @param mshr The MSHR to allocate the target to. + * @param req The target request. + */ + void allocateTarget(MSHR* mshr, Packet * &pkt) + { + mshr->allocateTarget(pkt); + allocatedTargets += 1; + } + + /** + * Remove a MSHR from the queue. Returns an iterator into the allocatedList + * for faster squash implementation. + * @param mshr The MSHR to remove. + * @return An iterator to the next entry in the allocatedList. + */ + MSHR::Iterator deallocateOne(MSHR* mshr); + + /** + * Moves the MSHR to the front of the pending list if it is not in service. + * @param mshr The mshr to move. + */ + void moveToFront(MSHR *mshr); + + /** + * Mark the given MSHR as in service. This removes the MSHR from the + * pendingList. Deallocates the MSHR if it does not expect a response. + * @param mshr The MSHR to mark in service. + */ + void markInService(MSHR* mshr); + + /** + * Mark an in service mshr as pending, used to resend a request. + * @param mshr The MSHR to resend. + * @param cmd The command to resend. + */ + void markPending(MSHR* mshr, Packet::Command cmd); + + /** + * Squash outstanding requests with the given thread number. If a request + * is in service, just squashes the targets. + * @param thread_number The thread to squash. + */ + void squash(int thread_number); + + /** + * Returns true if the pending list is not empty. + * @return True if there are outstanding requests. + */ + bool havePending() const + { + return !pendingList.empty(); + } + + /** + * Returns true if there are no free MSHRs. + * @return True if this queue is full. + */ + bool isFull() const + { + return (allocated > numMSHRs - numReserve); + } + + /** + * Returns the request at the head of the pendingList. + * @return The next request to service. + */ + Packet * getReq() const + { + if (pendingList.empty()) { + return NULL; + } + MSHR* mshr = pendingList.front(); + return mshr->pkt; + } + + /** + * Returns the number of outstanding targets. + * @return the number of allocated targets. + */ + int getAllocatedTargets() const + { + return allocatedTargets; + } + +}; + +#endif //__MSHR_QUEUE_HH__ |