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/*
* 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) 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, std::vector<MSHR*>& matches) const;
/**
* Find any pending requests that overlap the given request.
* @param pkt The request to find.
* @return A pointer to the earliest matching MSHR.
*/
MSHR* findPending(PacketPtr &pkt) const;
/**
* Allocates a new MSHR for the request and size. This places the request
* as the first target in the MSHR.
* @param pkt 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(PacketPtr &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 size, PacketPtr &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 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 pkt The target request.
*/
void allocateTarget(MSHR* mshr, PacketPtr &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, MemCmd cmd);
/**
* Squash outstanding requests with the given thread number. If a request
* is in service, just squashes the targets.
* @param threadNum The thread to squash.
*/
void squash(int threadNum);
/**
* 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.
*/
PacketPtr 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__
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