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40 * Authors: Erik Hallnor
45 * Declaration of a structure to manage MSHRs.
48 #ifndef __MEM_CACHE_MSHR_QUEUE_HH__
49 #define __MEM_CACHE_MSHR_QUEUE_HH__
53 #include "base/types.hh"
54 #include "mem/cache/mshr.hh"
55 #include "mem/cache/queue.hh"
56 #include "mem/packet.hh"
59 * A Class for maintaining a list of pending and allocated memory requests.
61 class MSHRQueue : public Queue<MSHR>
66 * The number of entries to reserve for future demand accesses.
67 * Prevent prefetcher from taking all mshr entries
69 const int demandReserve;
74 * Create a queue with a given number of entries.
75 * @param num_entrys The number of entries in this queue.
76 * @param reserve The minimum number of entries needed to satisfy
78 * @param demand_reserve The minimum number of entries needed to satisfy
81 MSHRQueue(const std::string &_label, int num_entries, int reserve,
85 * Allocates a new MSHR for the request and size. This places the request
86 * as the first target in the MSHR.
88 * @param blk_addr The address of the block.
89 * @param blk_size The number of bytes to request.
90 * @param pkt The original miss.
91 * @param when_ready When should the MSHR be ready to act upon.
92 * @param order The logical order of this MSHR
93 * @param alloc_on_fill Should the cache allocate a block on fill
95 * @return The a pointer to the MSHR allocated.
97 * @pre There are free entries.
99 MSHR *allocate(Addr blk_addr, unsigned blk_size, PacketPtr pkt,
100 Tick when_ready, Counter order, bool alloc_on_fill);
103 * Moves the MSHR to the front of the pending list if it is not
105 * @param mshr The entry to move.
107 void moveToFront(MSHR *mshr);
110 * Adds a delay to the provided MSHR and moves MSHRs that will be
111 * ready earlier than this entry to the top of the list
113 * @param mshr that needs to be delayed
114 * @param delay_ticks ticks of the desired delay
116 void delay(MSHR *mshr, Tick delay_ticks);
119 * Mark the given MSHR as in service. This removes the MSHR from the
120 * readyList or deallocates the MSHR if it does not expect a response.
122 * @param mshr The MSHR to mark in service.
123 * @param pending_modified_resp Whether we expect a modified response
126 void markInService(MSHR *mshr, bool pending_modified_resp);
129 * Mark an in service entry as pending, used to resend a request.
130 * @param mshr The MSHR to resend.
132 void markPending(MSHR *mshr);
135 * Deallocate top target, possibly freeing the MSHR
136 * @return if MSHR queue is no longer full
138 bool forceDeallocateTarget(MSHR *mshr);
141 * Returns true if the pending list is not empty.
142 * @return True if there are outstanding requests.
144 bool havePending() const
146 return !readyList.empty();
150 * Returns true if sufficient mshrs for prefetch.
151 * @return True if sufficient mshrs for prefetch.
153 bool canPrefetch() const
155 // @todo we may want to revisit the +1, currently added to
156 // keep regressions unchanged
157 return (allocated < numEntries - (numReserve + 1 + demandReserve));
161 #endif //__MEM_CACHE_MSHR_QUEUE_HH__