snoop_filter.hh revision 11129:48c02e8b0bbb
16876Ssteve.reinhardt@amd.com/* 210089Sandreas.hansson@arm.com * Copyright (c) 2013-2015 ARM Limited 38922Swilliam.wang@arm.com * All rights reserved 48922Swilliam.wang@arm.com * 58922Swilliam.wang@arm.com * The license below extends only to copyright in the software and shall 68922Swilliam.wang@arm.com * not be construed as granting a license to any other intellectual 78922Swilliam.wang@arm.com * property including but not limited to intellectual property relating 88922Swilliam.wang@arm.com * to a hardware implementation of the functionality of the software 98922Swilliam.wang@arm.com * licensed hereunder. You may use the software subject to the license 108922Swilliam.wang@arm.com * terms below provided that you ensure that this notice is replicated 118922Swilliam.wang@arm.com * unmodified and in its entirety in all distributions of the software, 128922Swilliam.wang@arm.com * modified or unmodified, in source code or in binary form. 138922Swilliam.wang@arm.com * 146876Ssteve.reinhardt@amd.com * Redistribution and use in source and binary forms, with or without 158717Snilay@cs.wisc.edu * modification, are permitted provided that the following conditions are 166876Ssteve.reinhardt@amd.com * met: redistributions of source code must retain the above copyright 176876Ssteve.reinhardt@amd.com * notice, this list of conditions and the following disclaimer; 186876Ssteve.reinhardt@amd.com * redistributions in binary form must reproduce the above copyright 196876Ssteve.reinhardt@amd.com * notice, this list of conditions and the following disclaimer in the 206876Ssteve.reinhardt@amd.com * documentation and/or other materials provided with the distribution; 216876Ssteve.reinhardt@amd.com * neither the name of the copyright holders nor the names of its 226876Ssteve.reinhardt@amd.com * contributors may be used to endorse or promote products derived from 236876Ssteve.reinhardt@amd.com * this software without specific prior written permission. 246876Ssteve.reinhardt@amd.com * 256876Ssteve.reinhardt@amd.com * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 266876Ssteve.reinhardt@amd.com * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 276876Ssteve.reinhardt@amd.com * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 286876Ssteve.reinhardt@amd.com * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 296876Ssteve.reinhardt@amd.com * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 306876Ssteve.reinhardt@amd.com * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 316876Ssteve.reinhardt@amd.com * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 326876Ssteve.reinhardt@amd.com * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 336876Ssteve.reinhardt@amd.com * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 346876Ssteve.reinhardt@amd.com * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 356876Ssteve.reinhardt@amd.com * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 366876Ssteve.reinhardt@amd.com * 376876Ssteve.reinhardt@amd.com * Authors: Stephan Diestelhorst <stephan.diestelhorst@arm.com> 386876Ssteve.reinhardt@amd.com */ 396876Ssteve.reinhardt@amd.com 406876Ssteve.reinhardt@amd.com/** 416876Ssteve.reinhardt@amd.com * @file 427039Snate@binkert.org * Definition of a snoop filter. 437039Snate@binkert.org */ 446285Snate@binkert.org 457039Snate@binkert.org#ifndef __MEM_SNOOP_FILTER_HH__ 466285Snate@binkert.org#define __MEM_SNOOP_FILTER_HH__ 476285Snate@binkert.org 486922SBrad.Beckmann@amd.com#include <utility> 4910301Snilay@cs.wisc.edu 507909Shestness@cs.utexas.edu#include "base/hashmap.hh" 518229Snate@binkert.org#include "mem/packet.hh" 527039Snate@binkert.org#include "mem/port.hh" 536876Ssteve.reinhardt@amd.com#include "mem/qport.hh" 546876Ssteve.reinhardt@amd.com#include "params/SnoopFilter.hh" 556876Ssteve.reinhardt@amd.com#include "sim/sim_object.hh" 566876Ssteve.reinhardt@amd.com#include "sim/system.hh" 577039Snate@binkert.org 587039Snate@binkert.org/** 597039Snate@binkert.org * This snoop filter keeps track of which connected port has a 6010090Snilay@cs.wisc.edu * particular line of data. It can be queried (through lookup*) on 6110090Snilay@cs.wisc.edu * memory requests from above (reads / writes / ...); and also from 6210090Snilay@cs.wisc.edu * below (snoops). The snoop filter precisely knows about the location 6310090Snilay@cs.wisc.edu * of lines "above" it through a map from cache line address to 6410090Snilay@cs.wisc.edu * sharers/ports. The snoop filter ties into the flows of requests 6510090Snilay@cs.wisc.edu * (when they succeed at the lower interface), regular responses from 6610090Snilay@cs.wisc.edu * below and also responses from sideway's caches (in update*). This 6710090Snilay@cs.wisc.edu * allows the snoop filter to model cache-line residency by snooping 6810090Snilay@cs.wisc.edu * the messages. 6910090Snilay@cs.wisc.edu * 7010090Snilay@cs.wisc.edu * The tracking happens in two fields to be able to distinguish 7110090Snilay@cs.wisc.edu * between in-flight requests (in requested) and already pulled in 7210090Snilay@cs.wisc.edu * lines (in holder). This distinction is used for producing tighter 7310090Snilay@cs.wisc.edu * assertions and tracking request completion. For safety, (requested 746882SBrad.Beckmann@amd.com * | holder) should be notified and the requesting MSHRs will take 757039Snate@binkert.org * care of ordering. 768975Sandreas.hansson@arm.com * 778436SBrad.Beckmann@amd.com * Overall, some trickery is required because: 7810525Snilay@cs.wisc.edu * (1) snoops are not followed by an ACK, but only evoke a response if 796882SBrad.Beckmann@amd.com * they need to (hit dirty) 806882SBrad.Beckmann@amd.com * (2) side-channel information is funnelled through direct modifications of 8110090Snilay@cs.wisc.edu * pkt, instead of proper messages through the bus 8210525Snilay@cs.wisc.edu * (3) there are no clean evict messages telling the snoop filter that a local, 836882SBrad.Beckmann@amd.com * upper cache dropped a line, making the snoop filter pessimistic for now 848717Snilay@cs.wisc.edu * (4) ordering: there is no single point of order in the system. Instead, 856882SBrad.Beckmann@amd.com * requesting MSHRs track order between local requests and remote snoops 866882SBrad.Beckmann@amd.com */ 8710089Sandreas.hansson@arm.comclass SnoopFilter : public SimObject { 8810090Snilay@cs.wisc.edu public: 8910090Snilay@cs.wisc.edu typedef std::vector<QueuedSlavePort*> SnoopList; 9010090Snilay@cs.wisc.edu 9110090Snilay@cs.wisc.edu SnoopFilter (const SnoopFilterParams *p) : SimObject(p), 9210089Sandreas.hansson@arm.com linesize(p->system->cacheLineSize()), lookupLatency(p->lookup_latency) 9310090Snilay@cs.wisc.edu { 9410090Snilay@cs.wisc.edu } 9510090Snilay@cs.wisc.edu 966882SBrad.Beckmann@amd.com /** 976882SBrad.Beckmann@amd.com * Init a new snoop filter and tell it about all the slave ports of the 9810089Sandreas.hansson@arm.com * enclosing bus. 996882SBrad.Beckmann@amd.com * 1006882SBrad.Beckmann@amd.com * @param bus_slave_ports Vector of slave ports that the bus is attached to. 10110090Snilay@cs.wisc.edu */ 1026882SBrad.Beckmann@amd.com void setSlavePorts(const SnoopList& bus_slave_ports) { 1037039Snate@binkert.org slavePorts = bus_slave_ports; 1048975Sandreas.hansson@arm.com } 1058914Sandreas.hansson@arm.com 1066882SBrad.Beckmann@amd.com /** 10710090Snilay@cs.wisc.edu * Lookup a request (from a slave port) in the snoop filter and return a 1086882SBrad.Beckmann@amd.com * list of other slave ports that need forwarding of the resulting snoops. 1096882SBrad.Beckmann@amd.com * Additionally, update the tracking structures with new request 11010090Snilay@cs.wisc.edu * information. 11110090Snilay@cs.wisc.edu * 1126882SBrad.Beckmann@amd.com * @param cpkt Pointer to the request packet. Not changed. 1136882SBrad.Beckmann@amd.com * @param slave_port Slave port where the request came from. 11410090Snilay@cs.wisc.edu * @return Pair of a vector of snoop target ports and lookup latency. 11510090Snilay@cs.wisc.edu */ 11610090Snilay@cs.wisc.edu std::pair<SnoopList, Cycles> lookupRequest(const Packet* cpkt, 11710090Snilay@cs.wisc.edu const SlavePort& slave_port); 11810090Snilay@cs.wisc.edu 11910090Snilay@cs.wisc.edu /** 12010090Snilay@cs.wisc.edu * For a successful request, update all data structures in the snoop filter 12110090Snilay@cs.wisc.edu * reflecting the changes caused by that request 12210090Snilay@cs.wisc.edu * 12310090Snilay@cs.wisc.edu * @param cpkt Pointer to the request packet. Not changed. 12410090Snilay@cs.wisc.edu * @param slave_port Slave port where the request came from. 12510090Snilay@cs.wisc.edu * @param will_retry This request will retry on this bus / snoop filter 12610090Snilay@cs.wisc.edu */ 12710090Snilay@cs.wisc.edu void updateRequest(const Packet* cpkt, const SlavePort& slave_port, 12810090Snilay@cs.wisc.edu bool will_retry); 12910090Snilay@cs.wisc.edu 13010090Snilay@cs.wisc.edu /** 13110090Snilay@cs.wisc.edu * Handle an incoming snoop from below (the master port). These can upgrade the 13210090Snilay@cs.wisc.edu * tracking logic and may also benefit from additional steering thanks to the 13310090Snilay@cs.wisc.edu * snoop filter. 13410090Snilay@cs.wisc.edu * @param cpkt Pointer to const Packet containing the snoop. 13510090Snilay@cs.wisc.edu * @return Pair with a vector of SlavePorts that need snooping and a lookup 13610090Snilay@cs.wisc.edu * latency. 13710090Snilay@cs.wisc.edu */ 13810090Snilay@cs.wisc.edu std::pair<SnoopList, Cycles> lookupSnoop(const Packet* cpkt); 13910090Snilay@cs.wisc.edu 14010090Snilay@cs.wisc.edu /** 1416876Ssteve.reinhardt@amd.com * Let the snoop filter see any snoop responses that turn into request responses 1426876Ssteve.reinhardt@amd.com * and indicate cache to cache transfers. These will update the corresponding 1436882SBrad.Beckmann@amd.com * state in the filter. 1446882SBrad.Beckmann@amd.com * 1456882SBrad.Beckmann@amd.com * @param cpkt Pointer to const Packet holding the snoop response. 1466285Snate@binkert.org * @param rsp_port SlavePort that sends the response. 1479294Sandreas.hansson@arm.com * @param req_port SlavePort that made the original request and is the 1489294Sandreas.hansson@arm.com * destination of the snoop response. 1499294Sandreas.hansson@arm.com */ 1509294Sandreas.hansson@arm.com void updateSnoopResponse(const Packet *cpkt, const SlavePort& rsp_port, 1516876Ssteve.reinhardt@amd.com const SlavePort& req_port); 1528615Snilay@cs.wisc.edu 1538688Snilay@cs.wisc.edu /** 1548688Snilay@cs.wisc.edu * Pass snoop responses that travel downward through the snoop filter and let 1558688Snilay@cs.wisc.edu * them update the snoop filter state. No additional routing happens. 1566882SBrad.Beckmann@amd.com * 1576882SBrad.Beckmann@amd.com * @param cpkt Pointer to const Packet holding the snoop response. 1586882SBrad.Beckmann@amd.com * @param rsp_port SlavePort that sends the response. 1596882SBrad.Beckmann@amd.com * @param req_port MasterPort through which the response leaves this cluster. 1606882SBrad.Beckmann@amd.com */ 1616882SBrad.Beckmann@amd.com void updateSnoopForward(const Packet *cpkt, const SlavePort& rsp_port, 16210012Snilay@cs.wisc.edu const MasterPort& req_port); 1639342SAndreas.Sandberg@arm.com 1646285Snate@binkert.org /** 1657039Snate@binkert.org * Update the snoop filter with a response from below (outer / other cache, 1667039Snate@binkert.org * or memory) and update the tracking information in the snoop filter. 1678688Snilay@cs.wisc.edu * 1688717Snilay@cs.wisc.edu * @param cpkt Pointer to const Packet holding the snoop response. 1696285Snate@binkert.org * @param slave_port SlavePort that made the original request and is the target 17010089Sandreas.hansson@arm.com * of this response. 17110089Sandreas.hansson@arm.com */ 17210089Sandreas.hansson@arm.com void updateResponse(const Packet *cpkt, const SlavePort& slave_port); 17310089Sandreas.hansson@arm.com 17410089Sandreas.hansson@arm.com /** 17510089Sandreas.hansson@arm.com * Simple factory methods for standard return values for lookupRequest 17610089Sandreas.hansson@arm.com */ 17710089Sandreas.hansson@arm.com std::pair<SnoopList, Cycles> snoopAll(Cycles latency) const 17810089Sandreas.hansson@arm.com { 17910089Sandreas.hansson@arm.com return std::make_pair(slavePorts, latency); 18010012Snilay@cs.wisc.edu } 1817039Snate@binkert.org std::pair<SnoopList, Cycles> snoopSelected(const SnoopList& slave_ports, 1827039Snate@binkert.org Cycles latency) const 1837910SBrad.Beckmann@amd.com { 18410467Sandreas.hansson@arm.com return std::make_pair(slave_ports, latency); 1856876Ssteve.reinhardt@amd.com } 1867039Snate@binkert.org std::pair<SnoopList, Cycles> snoopDown(Cycles latency) const 18710090Snilay@cs.wisc.edu { 1887910SBrad.Beckmann@amd.com SnoopList empty; 18910089Sandreas.hansson@arm.com return std::make_pair(empty , latency); 19010089Sandreas.hansson@arm.com } 19110089Sandreas.hansson@arm.com 1927910SBrad.Beckmann@amd.com virtual void regStats(); 1937910SBrad.Beckmann@amd.com 1949342SAndreas.Sandberg@arm.com protected: 1958688Snilay@cs.wisc.edu typedef uint64_t SnoopMask; 19610090Snilay@cs.wisc.edu /** 19710090Snilay@cs.wisc.edu * Per cache line item tracking a bitmask of SlavePorts who have an 19810090Snilay@cs.wisc.edu * outstanding request to this line (requested) or already share a cache line 19910090Snilay@cs.wisc.edu * with this address (holder). 20010090Snilay@cs.wisc.edu */ 20110090Snilay@cs.wisc.edu struct SnoopItem { 2028922Swilliam.wang@arm.com SnoopMask requested; 20310090Snilay@cs.wisc.edu SnoopMask holder; 20410090Snilay@cs.wisc.edu }; 20510090Snilay@cs.wisc.edu /** 2068686Snilay@cs.wisc.edu * HashMap of SnoopItems indexed by line address 2079342SAndreas.Sandberg@arm.com */ 2087910SBrad.Beckmann@amd.com typedef m5::hash_map<Addr, SnoopItem> SnoopFilterCache; 2097910SBrad.Beckmann@amd.com 2107910SBrad.Beckmann@amd.com /** 2117910SBrad.Beckmann@amd.com * Convert a single port to a corresponding, one-hot bitmask 2127910SBrad.Beckmann@amd.com * @param port SlavePort that should be converted. 21310090Snilay@cs.wisc.edu * @return One-hot bitmask corresponding to the port. 2146285Snate@binkert.org */ 2156285Snate@binkert.org SnoopMask portToMask(const SlavePort& port) const; 2167039Snate@binkert.org /** 217 * Convert multiple ports to a corresponding bitmask 218 * @param ports SnoopList that should be converted. 219 * @return Bitmask corresponding to the ports in the list. 220 */ 221 SnoopMask portListToMask(const SnoopList& ports) const; 222 /** 223 * Converts a bitmask of ports into the corresponing list of ports 224 * @param ports SnoopMask of the requested ports 225 * @return SnoopList containing all the requested SlavePorts 226 */ 227 SnoopList maskToPortList(SnoopMask ports) const; 228 229 private: 230 231 /** 232 * Removes snoop filter items which have no requesters and no holders. 233 */ 234 void eraseIfNullEntry(SnoopFilterCache::iterator& sf_it); 235 /** Simple hash set of cached addresses. */ 236 SnoopFilterCache cachedLocations; 237 /** 238 * Variable to temporarily store value of snoopfilter entry 239 * incase updateRequest needs to undo changes made in lookupRequest 240 * (because of crossbar retry) 241 */ 242 SnoopItem retryItem; 243 /** List of all attached slave ports. */ 244 SnoopList slavePorts; 245 /** Cache line size. */ 246 const unsigned linesize; 247 /** Latency for doing a lookup in the filter */ 248 const Cycles lookupLatency; 249 250 /** Statistics */ 251 Stats::Scalar totRequests; 252 Stats::Scalar hitSingleRequests; 253 Stats::Scalar hitMultiRequests; 254 255 Stats::Scalar totSnoops; 256 Stats::Scalar hitSingleSnoops; 257 Stats::Scalar hitMultiSnoops; 258}; 259 260inline SnoopFilter::SnoopMask 261SnoopFilter::portToMask(const SlavePort& port) const 262{ 263 unsigned id = (unsigned)port.getId(); 264 assert(id != (unsigned)InvalidPortID); 265 assert((int)id < 8 * sizeof(SnoopMask)); 266 267 return ((SnoopMask)1) << id; 268} 269 270inline SnoopFilter::SnoopMask 271SnoopFilter::portListToMask(const SnoopList& ports) const 272{ 273 SnoopMask m = 0; 274 for (auto port = ports.begin(); port != ports.end(); ++port) 275 m |= portToMask(**port); 276 return m; 277} 278 279inline SnoopFilter::SnoopList 280SnoopFilter::maskToPortList(SnoopMask port_mask) const 281{ 282 SnoopList res; 283 for (auto port = slavePorts.begin(); port != slavePorts.end(); ++port) 284 if (port_mask & portToMask(**port)) 285 res.push_back(*port); 286 return res; 287} 288#endif // __MEM_SNOOP_FILTER_HH__ 289