1/* 2 * Copyright (c) 2013-2015 ARM Limited 3 * All rights reserved 4 * 5 * The license below extends only to copyright in the software and shall 6 * not be construed as granting a license to any other intellectual 7 * property including but not limited to intellectual property relating 8 * to a hardware implementation of the functionality of the software --- 74 unchanged lines hidden (view full) --- 83 * upper cache dropped a line, making the snoop filter pessimistic for now 84 * (4) ordering: there is no single point of order in the system. Instead, 85 * requesting MSHRs track order between local requests and remote snoops 86 */ 87class SnoopFilter : public SimObject { 88 public: 89 typedef std::vector<QueuedSlavePort*> SnoopList; 90 |
91 SnoopFilter (const SnoopFilterParams *p) : 92 SimObject(p), reqLookupResult(cachedLocations.end()), retryItem{0, 0}, |
93 linesize(p->system->cacheLineSize()), lookupLatency(p->lookup_latency) 94 { 95 } 96 97 /** 98 * Init a new snoop filter and tell it about all the slave ports of the 99 * enclosing bus. 100 * 101 * @param bus_slave_ports Vector of slave ports that the bus is attached to. 102 */ 103 void setSlavePorts(const SnoopList& bus_slave_ports) { 104 slavePorts = bus_slave_ports; 105 } 106 107 /** |
108 * Lookup a request (from a slave port) in the snoop filter and 109 * return a list of other slave ports that need forwarding of the 110 * resulting snoops. Additionally, update the tracking structures 111 * with new request information. Note that the caller must also 112 * call finishRequest once it is known if the request needs to 113 * retry or not. |
114 * 115 * @param cpkt Pointer to the request packet. Not changed. 116 * @param slave_port Slave port where the request came from. 117 * @return Pair of a vector of snoop target ports and lookup latency. 118 */ 119 std::pair<SnoopList, Cycles> lookupRequest(const Packet* cpkt, 120 const SlavePort& slave_port); 121 122 /** |
123 * For an un-successful request, revert the change to the snoop 124 * filter. Also take care of erasing any null entries. This method 125 * relies on the result from lookupRequest being stored in 126 * reqLookupResult. |
127 * |
128 * @param will_retry This request will retry on this bus / snoop filter |
129 * @param cpkt Request packet, merely for sanity checking |
130 */ |
131 void finishRequest(bool will_retry, const Packet* cpkt); |
132 133 /** 134 * Handle an incoming snoop from below (the master port). These can upgrade the 135 * tracking logic and may also benefit from additional steering thanks to the 136 * snoop filter. 137 * @param cpkt Pointer to const Packet containing the snoop. 138 * @return Pair with a vector of SlavePorts that need snooping and a lookup 139 * latency. --- 93 unchanged lines hidden (view full) --- 233 234 /** 235 * Removes snoop filter items which have no requesters and no holders. 236 */ 237 void eraseIfNullEntry(SnoopFilterCache::iterator& sf_it); 238 /** Simple hash set of cached addresses. */ 239 SnoopFilterCache cachedLocations; 240 /** |
241 * Iterator used to store the result from lookupRequest until we 242 * call finishRequest. 243 */ 244 SnoopFilterCache::iterator reqLookupResult; 245 /** |
246 * Variable to temporarily store value of snoopfilter entry |
247 * incase finishRequest needs to undo changes made in lookupRequest |
248 * (because of crossbar retry) 249 */ 250 SnoopItem retryItem; 251 /** List of all attached slave ports. */ 252 SnoopList slavePorts; 253 /** Cache line size. */ 254 const unsigned linesize; 255 /** Latency for doing a lookup in the filter */ --- 41 unchanged lines hidden --- |