gem5  v22.1.0.0
snoop_filter.hh
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37 
43 #ifndef __MEM_SNOOP_FILTER_HH__
44 #define __MEM_SNOOP_FILTER_HH__
45 
46 #include <bitset>
47 #include <unordered_map>
48 #include <utility>
49 
50 #include "mem/packet.hh"
51 #include "mem/port.hh"
52 #include "mem/qport.hh"
53 #include "params/SnoopFilter.hh"
54 #include "sim/sim_object.hh"
55 #include "sim/system.hh"
56 
57 namespace gem5
58 {
59 
89 class SnoopFilter : public SimObject
90 {
91  public:
92 
93  // Change for systems with more than 256 ports tracked by this object
94  static const int SNOOP_MASK_SIZE = 256;
95 
97 
98  SnoopFilter (const SnoopFilterParams &p) :
100  linesize(p.system->cacheLineSize()), lookupLatency(p.lookup_latency),
101  maxEntryCount(p.max_capacity / p.system->cacheLineSize()),
102  stats(this)
103  {
104  }
105 
112  void setCPUSidePorts(const SnoopList& _cpu_side_ports) {
113  localResponsePortIds.resize(_cpu_side_ports.size(), InvalidPortID);
114 
115  PortID id = 0;
116  for (const auto& p : _cpu_side_ports) {
117  // no need to track this port if it is not snooping
118  if (p->isSnooping()) {
119  cpuSidePorts.push_back(p);
120  localResponsePortIds[p->getId()] = id++;
121  }
122  }
123 
124  // make sure we can deal with this many ports
126  "Snoop filter only supports %d snooping ports, got %d\n",
127  SNOOP_MASK_SIZE, id);
128  }
129 
143  const ResponsePort& cpu_side_port);
144 
154  void finishRequest(bool will_retry, Addr addr, bool is_secure);
155 
166 
177  void updateSnoopResponse(const Packet *cpkt, const ResponsePort& rsp_port,
178  const ResponsePort& req_port);
179 
189  void updateSnoopForward(const Packet *cpkt, const ResponsePort& rsp_port,
190  const RequestPort& req_port);
191 
201  void updateResponse(const Packet *cpkt, const ResponsePort& cpu_side_port);
202 
203  virtual void regStats();
204 
205  protected:
206 
211  typedef std::bitset<SNOOP_MASK_SIZE> SnoopMask;
212 
218  struct SnoopItem
219  {
222  };
226  typedef std::unordered_map<Addr, SnoopItem> SnoopFilterCache;
227 
232  {
233  return std::make_pair(cpuSidePorts, latency);
234  }
236  _cpu_side_ports, Cycles latency) const
237  {
238  return std::make_pair(_cpu_side_ports, latency);
239  }
241  {
242  SnoopList empty;
243  return std::make_pair(empty , latency);
244  }
245 
251  SnoopMask portToMask(const ResponsePort& port) const;
257  SnoopList maskToPortList(SnoopMask ports) const;
258 
259  private:
260 
264  void eraseIfNullEntry(SnoopFilterCache::iterator& sf_it);
265 
268 
276  {
278  SnoopFilterCache::iterator it;
279 
286 
293  ReqLookupResult(SnoopFilterCache::iterator end_it)
294  : it(end_it), retryItem{0, 0}
295  {
296  }
297  ReqLookupResult() = delete;
299 
305  const unsigned linesize;
309  const unsigned maxEntryCount;
310 
315  {
317  LineSecure = 0x01,
318  };
319 
322  {
324 
328 
332  } stats;
333 };
334 
337 {
338  assert(port.getId() != InvalidPortID);
339  // if this is not a snooping port, return a zero mask
340  return !port.isSnooping() ? 0 :
341  ((SnoopMask)1) << localResponsePortIds[port.getId()];
342 }
343 
346 {
347  SnoopList res;
348  for (const auto& p : cpuSidePorts)
349  if ((port_mask & portToMask(*p)).any())
350  res.push_back(p);
351  return res;
352 }
353 
354 } // namespace gem5
355 
356 #endif // __MEM_SNOOP_FILTER_HH__
Cycles is a wrapper class for representing cycle counts, i.e.
Definition: types.hh:79
A Packet is used to encapsulate a transfer between two objects in the memory system (e....
Definition: packet.hh:294
PortID getId() const
Get the port id.
Definition: port.hh:114
A RequestPort is a specialisation of a Port, which implements the default protocol for the three diff...
Definition: port.hh:79
A ResponsePort is a specialization of a port.
Definition: port.hh:270
bool isSnooping() const
Find out if the peer request port is snooping or not.
Definition: port.hh:291
Abstract superclass for simulation objects.
Definition: sim_object.hh:148
This snoop filter keeps track of which connected port has a particular line of data.
Definition: snoop_filter.hh:90
void finishRequest(bool will_retry, Addr addr, bool is_secure)
For an un-successful request, revert the change to the snoop filter.
std::vector< PortID > localResponsePortIds
Track the mapping from port ids to the local mask ids.
void setCPUSidePorts(const SnoopList &_cpu_side_ports)
Init a new snoop filter and tell it about all the cpu_sideports of the enclosing bus.
SnoopFilter(const SnoopFilterParams &p)
Definition: snoop_filter.hh:98
void eraseIfNullEntry(SnoopFilterCache::iterator &sf_it)
Removes snoop filter items which have no requestors and no holders.
Definition: snoop_filter.cc:56
const unsigned linesize
Cache line size.
std::vector< QueuedResponsePort * > SnoopList
Definition: snoop_filter.hh:96
SnoopList cpuSidePorts
List of all attached snooping CPU-side ports.
const Cycles lookupLatency
Latency for doing a lookup in the filter.
std::pair< SnoopList, Cycles > snoopSelected(const SnoopList &_cpu_side_ports, Cycles latency) const
SnoopMask portToMask(const ResponsePort &port) const
Convert a single port to a corresponding, one-hot bitmask.
void updateSnoopForward(const Packet *cpkt, const ResponsePort &rsp_port, const RequestPort &req_port)
Pass snoop responses that travel downward through the snoop filter and let them update the snoop filt...
void updateResponse(const Packet *cpkt, const ResponsePort &cpu_side_port)
Update the snoop filter with a response from below (outer / other cache, or memory) and update the tr...
std::unordered_map< Addr, SnoopItem > SnoopFilterCache
HashMap of SnoopItems indexed by line address.
std::pair< SnoopList, Cycles > snoopDown(Cycles latency) const
std::bitset< SNOOP_MASK_SIZE > SnoopMask
The underlying type for the bitmask we use for tracking.
std::pair< SnoopList, Cycles > lookupSnoop(const Packet *cpkt)
Handle an incoming snoop from below (the memory-side port).
SnoopList maskToPortList(SnoopMask ports) const
Converts a bitmask of ports into the corresponing list of ports.
struct gem5::SnoopFilter::ReqLookupResult reqLookupResult
std::pair< SnoopList, Cycles > snoopAll(Cycles latency) const
Simple factory methods for standard return values.
const unsigned maxEntryCount
Max capacity in terms of cache blocks tracked, for sanity checking.
SnoopFilterCache cachedLocations
Simple hash set of cached addresses.
void updateSnoopResponse(const Packet *cpkt, const ResponsePort &rsp_port, const ResponsePort &req_port)
Let the snoop filter see any snoop responses that turn into request responses and indicate cache to c...
LineStatus
Use the lower bits of the address to keep track of the line status.
@ LineSecure
block holds data from the secure memory space
gem5::SnoopFilter::SnoopFilterStats stats
static const int SNOOP_MASK_SIZE
Definition: snoop_filter.hh:94
std::pair< SnoopList, Cycles > lookupRequest(const Packet *cpkt, const ResponsePort &cpu_side_port)
Lookup a request (from a CPU-side port) in the snoop filter and return a list of other CPU-side ports...
Definition: snoop_filter.cc:67
virtual void regStats()
Callback to set stat parameters.
Statistics container.
Definition: group.hh:94
This is a simple scalar statistic, like a counter.
Definition: statistics.hh:1931
STL pair class.
Definition: stl.hh:58
#define fatal_if(cond,...)
Conditional fatal macro that checks the supplied condition and only causes a fatal error if the condi...
Definition: logging.hh:226
Port Object Declaration.
Bitfield< 54 > p
Definition: pagetable.hh:70
Bitfield< 15 > system
Definition: misc.hh:1004
Bitfield< 3 > addr
Definition: types.hh:84
Reference material can be found at the JEDEC website: UFS standard http://www.jedec....
const PortID InvalidPortID
Definition: types.hh:246
uint64_t Addr
Address type This will probably be moved somewhere else in the near future.
Definition: types.hh:147
int16_t PortID
Port index/ID type, and a symbolic name for an invalid port id.
Definition: types.hh:245
Declaration of the Packet class.
Declaration of the queued port.
A request lookup must be followed by a call to finishRequest to inform the operation's success.
SnoopItem retryItem
Variable to temporarily store value of snoopfilter entry in case finishRequest needs to undo changes ...
ReqLookupResult(SnoopFilterCache::iterator end_it)
The constructor must be informed of the internal cache's end iterator, so do not allow the compiler t...
SnoopFilterCache::iterator it
Iterator used to store the result from lookupRequest.
SnoopFilterStats(statistics::Group *parent)
Per cache line item tracking a bitmask of ResponsePorts who have an outstanding request to this line ...

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