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47 * Definition of a crossbar object.
50 #include "mem/xbar.hh"
52 #include "base/logging.hh"
53 #include "base/trace.hh"
54 #include "debug/AddrRanges.hh"
55 #include "debug/Drain.hh"
56 #include "debug/XBar.hh"
58 BaseXBar::BaseXBar(const BaseXBarParams
*p
)
60 frontendLatency(p
->frontend_latency
),
61 forwardLatency(p
->forward_latency
),
62 responseLatency(p
->response_latency
),
64 gotAddrRanges(p
->port_default_connection_count
+
65 p
->port_master_connection_count
, false),
66 gotAllAddrRanges(false), defaultPortID(InvalidPortID
),
67 useDefaultRange(p
->use_default_range
)
72 for (auto m
: masterPorts
)
75 for (auto s
: slavePorts
)
85 BaseXBar::getMasterPort(const std::string
&if_name
, PortID idx
)
87 if (if_name
== "master" && idx
< masterPorts
.size()) {
88 // the master port index translates directly to the vector position
89 return *masterPorts
[idx
];
90 } else if (if_name
== "default") {
91 return *masterPorts
[defaultPortID
];
93 return MemObject::getMasterPort(if_name
, idx
);
98 BaseXBar::getSlavePort(const std::string
&if_name
, PortID idx
)
100 if (if_name
== "slave" && idx
< slavePorts
.size()) {
101 // the slave port index translates directly to the vector position
102 return *slavePorts
[idx
];
104 return MemObject::getSlavePort(if_name
, idx
);
109 BaseXBar::calcPacketTiming(PacketPtr pkt
, Tick header_delay
)
111 // the crossbar will be called at a time that is not necessarily
112 // coinciding with its own clock, so start by determining how long
113 // until the next clock edge (could be zero)
114 Tick offset
= clockEdge() - curTick();
116 // the header delay depends on the path through the crossbar, and
117 // we therefore rely on the caller to provide the actual
119 pkt
->headerDelay
+= offset
+ header_delay
;
121 // note that we add the header delay to the existing value, and
122 // align it to the crossbar clock
124 // do a quick sanity check to ensure the timings are not being
125 // ignored, note that this specific value may cause problems for
126 // slower interconnects
127 panic_if(pkt
->headerDelay
> SimClock::Int::us
,
128 "Encountered header delay exceeding 1 us\n");
130 if (pkt
->hasData()) {
131 // the payloadDelay takes into account the relative time to
132 // deliver the payload of the packet, after the header delay,
133 // we take the maximum since the payload delay could already
134 // be longer than what this parcitular crossbar enforces.
135 pkt
->payloadDelay
= std::max
<Tick
>(pkt
->payloadDelay
,
136 divCeil(pkt
->getSize(), width
) *
140 // the payload delay is not paying for the clock offset as that is
141 // already done using the header delay, and the payload delay is
142 // also used to determine how long the crossbar layer is busy and
143 // thus regulates throughput
146 template <typename SrcType
, typename DstType
>
147 BaseXBar::Layer
<SrcType
,DstType
>::Layer(DstType
& _port
, BaseXBar
& _xbar
,
148 const std::string
& _name
) :
149 port(_port
), xbar(_xbar
), _name(_name
), state(IDLE
),
150 waitingForPeer(NULL
), releaseEvent([this]{ releaseLayer(); }, name())
154 template <typename SrcType
, typename DstType
>
155 void BaseXBar::Layer
<SrcType
,DstType
>::occupyLayer(Tick until
)
157 // ensure the state is busy at this point, as the layer should
158 // transition from idle as soon as it has decided to forward the
159 // packet to prevent any follow-on calls to sendTiming seeing an
161 assert(state
== BUSY
);
163 // until should never be 0 as express snoops never occupy the layer
165 xbar
.schedule(releaseEvent
, until
);
167 // account for the occupied ticks
168 occupancy
+= until
- curTick();
170 DPRINTF(BaseXBar
, "The crossbar layer is now busy from tick %d to %d\n",
174 template <typename SrcType
, typename DstType
>
176 BaseXBar::Layer
<SrcType
,DstType
>::tryTiming(SrcType
* src_port
)
178 // if we are in the retry state, we will not see anything but the
179 // retrying port (or in the case of the snoop ports the snoop
180 // response port that mirrors the actual slave port) as we leave
181 // this state again in zero time if the peer does not immediately
182 // call the layer when receiving the retry
184 // first we see if the layer is busy, next we check if the
185 // destination port is already engaged in a transaction waiting
186 // for a retry from the peer
187 if (state
== BUSY
|| waitingForPeer
!= NULL
) {
188 // the port should not be waiting already
189 assert(std::find(waitingForLayer
.begin(), waitingForLayer
.end(),
190 src_port
) == waitingForLayer
.end());
192 // put the port at the end of the retry list waiting for the
193 // layer to be freed up (and in the case of a busy peer, for
194 // that transaction to go through, and then the layer to free
196 waitingForLayer
.push_back(src_port
);
205 template <typename SrcType
, typename DstType
>
207 BaseXBar::Layer
<SrcType
,DstType
>::succeededTiming(Tick busy_time
)
209 // we should have gone from idle or retry to busy in the tryTiming
211 assert(state
== BUSY
);
213 // occupy the layer accordingly
214 occupyLayer(busy_time
);
217 template <typename SrcType
, typename DstType
>
219 BaseXBar::Layer
<SrcType
,DstType
>::failedTiming(SrcType
* src_port
,
222 // ensure no one got in between and tried to send something to
224 assert(waitingForPeer
== NULL
);
226 // if the source port is the current retrying one or not, we have
227 // failed in forwarding and should track that we are now waiting
228 // for the peer to send a retry
229 waitingForPeer
= src_port
;
231 // we should have gone from idle or retry to busy in the tryTiming
233 assert(state
== BUSY
);
235 // occupy the bus accordingly
236 occupyLayer(busy_time
);
239 template <typename SrcType
, typename DstType
>
241 BaseXBar::Layer
<SrcType
,DstType
>::releaseLayer()
243 // releasing the bus means we should now be idle
244 assert(state
== BUSY
);
245 assert(!releaseEvent
.scheduled());
250 // bus layer is now idle, so if someone is waiting we can retry
251 if (!waitingForLayer
.empty()) {
252 // there is no point in sending a retry if someone is still
253 // waiting for the peer
254 if (waitingForPeer
== NULL
)
256 } else if (waitingForPeer
== NULL
&& drainState() == DrainState::Draining
) {
257 DPRINTF(Drain
, "Crossbar done draining, signaling drain manager\n");
258 //If we weren't able to drain before, do it now.
263 template <typename SrcType
, typename DstType
>
265 BaseXBar::Layer
<SrcType
,DstType
>::retryWaiting()
267 // this should never be called with no one waiting
268 assert(!waitingForLayer
.empty());
270 // we always go to retrying from idle
271 assert(state
== IDLE
);
276 // set the retrying port to the front of the retry list and pop it
278 SrcType
* retryingPort
= waitingForLayer
.front();
279 waitingForLayer
.pop_front();
281 // tell the port to retry, which in some cases ends up calling the
283 sendRetry(retryingPort
);
285 // If the layer is still in the retry state, sendTiming wasn't
286 // called in zero time (e.g. the cache does this when a writeback
288 if (state
== RETRY
) {
289 // update the state to busy and reset the retrying port, we
290 // have done our bit and sent the retry
293 // occupy the crossbar layer until the next clock edge
294 occupyLayer(xbar
.clockEdge());
298 template <typename SrcType
, typename DstType
>
300 BaseXBar::Layer
<SrcType
,DstType
>::recvRetry()
302 // we should never get a retry without having failed to forward
303 // something to this port
304 assert(waitingForPeer
!= NULL
);
306 // add the port where the failed packet originated to the front of
307 // the waiting ports for the layer, this allows us to call retry
308 // on the port immediately if the crossbar layer is idle
309 waitingForLayer
.push_front(waitingForPeer
);
311 // we are no longer waiting for the peer
312 waitingForPeer
= NULL
;
314 // if the layer is idle, retry this port straight away, if we
315 // are busy, then simply let the port wait for its turn
319 assert(state
== BUSY
);
324 BaseXBar::findPort(Addr addr
)
326 // we should never see any address lookups before we've got the
327 // ranges of all connected slave modules
328 assert(gotAllAddrRanges
);
330 // Check the address map interval tree
331 auto i
= portMap
.contains(addr
);
332 if (i
!= portMap
.end()) {
336 // Check if this matches the default range
337 if (useDefaultRange
) {
338 if (defaultRange
.contains(addr
)) {
339 DPRINTF(AddrRanges
, " found addr %#llx on default\n",
341 return defaultPortID
;
343 } else if (defaultPortID
!= InvalidPortID
) {
344 DPRINTF(AddrRanges
, "Unable to find destination for addr %#llx, "
345 "will use default port\n", addr
);
346 return defaultPortID
;
349 // we should use the range for the default port and it did not
350 // match, or the default port is not set
351 fatal("Unable to find destination for addr %#llx on %s\n", addr
,
355 /** Function called by the port when the crossbar is receiving a range change.*/
357 BaseXBar::recvRangeChange(PortID master_port_id
)
359 DPRINTF(AddrRanges
, "Received range change from slave port %s\n",
360 masterPorts
[master_port_id
]->getSlavePort().name());
362 // remember that we got a range from this master port and thus the
363 // connected slave module
364 gotAddrRanges
[master_port_id
] = true;
366 // update the global flag
367 if (!gotAllAddrRanges
) {
368 // take a logical AND of all the ports and see if we got
369 // ranges from everyone
370 gotAllAddrRanges
= true;
371 std::vector
<bool>::const_iterator r
= gotAddrRanges
.begin();
372 while (gotAllAddrRanges
&& r
!= gotAddrRanges
.end()) {
373 gotAllAddrRanges
&= *r
++;
375 if (gotAllAddrRanges
)
376 DPRINTF(AddrRanges
, "Got address ranges from all slaves\n");
379 // note that we could get the range from the default port at any
380 // point in time, and we cannot assume that the default range is
381 // set before the other ones are, so we do additional checks once
382 // all ranges are provided
383 if (master_port_id
== defaultPortID
) {
384 // only update if we are indeed checking ranges for the
385 // default port since the port might not have a valid range
387 if (useDefaultRange
) {
388 AddrRangeList ranges
= masterPorts
[master_port_id
]->getAddrRanges();
390 if (ranges
.size() != 1)
391 fatal("Crossbar %s may only have a single default range",
394 defaultRange
= ranges
.front();
397 // the ports are allowed to update their address ranges
398 // dynamically, so remove any existing entries
399 if (gotAddrRanges
[master_port_id
]) {
400 for (auto p
= portMap
.begin(); p
!= portMap
.end(); ) {
401 if (p
->second
== master_port_id
)
402 // erasing invalidates the iterator, so advance it
403 // before the deletion takes place
410 AddrRangeList ranges
= masterPorts
[master_port_id
]->getAddrRanges();
412 for (const auto& r
: ranges
) {
413 DPRINTF(AddrRanges
, "Adding range %s for id %d\n",
414 r
.to_string(), master_port_id
);
415 if (portMap
.insert(r
, master_port_id
) == portMap
.end()) {
416 PortID conflict_id
= portMap
.intersects(r
)->second
;
417 fatal("%s has two ports responding within range "
421 masterPorts
[master_port_id
]->getSlavePort().name(),
422 masterPorts
[conflict_id
]->getSlavePort().name());
427 // if we have received ranges from all our neighbouring slave
428 // modules, go ahead and tell our connected master modules in
429 // turn, this effectively assumes a tree structure of the system
430 if (gotAllAddrRanges
) {
431 DPRINTF(AddrRanges
, "Aggregating address ranges\n");
434 // start out with the default range
435 if (useDefaultRange
) {
436 if (!gotAddrRanges
[defaultPortID
])
437 fatal("Crossbar %s uses default range, but none provided",
440 xbarRanges
.push_back(defaultRange
);
441 DPRINTF(AddrRanges
, "-- Adding default %s\n",
442 defaultRange
.to_string());
445 // merge all interleaved ranges and add any range that is not
446 // a subset of the default range
447 std::vector
<AddrRange
> intlv_ranges
;
448 for (const auto& r
: portMap
) {
449 // if the range is interleaved then save it for now
450 if (r
.first
.interleaved()) {
451 // if we already got interleaved ranges that are not
452 // part of the same range, then first do a merge
453 // before we add the new one
454 if (!intlv_ranges
.empty() &&
455 !intlv_ranges
.back().mergesWith(r
.first
)) {
456 DPRINTF(AddrRanges
, "-- Merging range from %d ranges\n",
457 intlv_ranges
.size());
458 AddrRange
merged_range(intlv_ranges
);
459 // next decide if we keep the merged range or not
460 if (!(useDefaultRange
&&
461 merged_range
.isSubset(defaultRange
))) {
462 xbarRanges
.push_back(merged_range
);
463 DPRINTF(AddrRanges
, "-- Adding merged range %s\n",
464 merged_range
.to_string());
466 intlv_ranges
.clear();
468 intlv_ranges
.push_back(r
.first
);
470 // keep the current range if not a subset of the default
471 if (!(useDefaultRange
&&
472 r
.first
.isSubset(defaultRange
))) {
473 xbarRanges
.push_back(r
.first
);
474 DPRINTF(AddrRanges
, "-- Adding range %s\n",
475 r
.first
.to_string());
480 // if there is still interleaved ranges waiting to be merged,
481 // go ahead and do it
482 if (!intlv_ranges
.empty()) {
483 DPRINTF(AddrRanges
, "-- Merging range from %d ranges\n",
484 intlv_ranges
.size());
485 AddrRange
merged_range(intlv_ranges
);
486 if (!(useDefaultRange
&& merged_range
.isSubset(defaultRange
))) {
487 xbarRanges
.push_back(merged_range
);
488 DPRINTF(AddrRanges
, "-- Adding merged range %s\n",
489 merged_range
.to_string());
493 // also check that no range partially intersects with the
494 // default range, this has to be done after all ranges are set
495 // as there are no guarantees for when the default range is
496 // update with respect to the other ones
497 if (useDefaultRange
) {
498 for (const auto& r
: xbarRanges
) {
499 // see if the new range is partially
500 // overlapping the default range
501 if (r
.intersects(defaultRange
) &&
502 !r
.isSubset(defaultRange
))
503 fatal("Range %s intersects the " \
504 "default range of %s but is not a " \
505 "subset\n", r
.to_string(), name());
509 // tell all our neighbouring master ports that our address
510 // ranges have changed
511 for (const auto& s
: slavePorts
)
512 s
->sendRangeChange();
517 BaseXBar::getAddrRanges() const
519 // we should never be asked without first having sent a range
520 // change, and the latter is only done once we have all the ranges
521 // of the connected devices
522 assert(gotAllAddrRanges
);
524 // at the moment, this never happens, as there are no cycles in
525 // the range queries and no devices on the master side of a crossbar
526 // (CPU, cache, bridge etc) actually care about the ranges of the
527 // ports they are connected to
529 DPRINTF(AddrRanges
, "Received address range request\n");
537 ClockedObject::regStats();
539 using namespace Stats
;
542 .init(MemCmd::NUM_MEM_CMDS
)
543 .name(name() + ".trans_dist")
544 .desc("Transaction distribution")
547 // get the string representation of the commands
548 for (int i
= 0; i
< MemCmd::NUM_MEM_CMDS
; i
++) {
550 const std::string
&cstr
= cmd
.toString();
551 transDist
.subname(i
, cstr
);
555 .init(slavePorts
.size(), masterPorts
.size())
556 .name(name() + ".pkt_count")
557 .desc("Packet count per connected master and slave (bytes)")
558 .flags(total
| nozero
| nonan
);
561 .init(slavePorts
.size(), masterPorts
.size())
562 .name(name() + ".pkt_size")
563 .desc("Cumulative packet size per connected master and slave (bytes)")
564 .flags(total
| nozero
| nonan
);
566 // both the packet count and total size are two-dimensional
567 // vectors, indexed by slave port id and master port id, thus the
568 // neighbouring master and slave, they do not differentiate what
569 // came from the master and was forwarded to the slave (requests
570 // and snoop responses) and what came from the slave and was
571 // forwarded to the master (responses and snoop requests)
572 for (int i
= 0; i
< slavePorts
.size(); i
++) {
573 pktCount
.subname(i
, slavePorts
[i
]->getMasterPort().name());
574 pktSize
.subname(i
, slavePorts
[i
]->getMasterPort().name());
575 for (int j
= 0; j
< masterPorts
.size(); j
++) {
576 pktCount
.ysubname(j
, masterPorts
[j
]->getSlavePort().name());
577 pktSize
.ysubname(j
, masterPorts
[j
]->getSlavePort().name());
582 template <typename SrcType
, typename DstType
>
584 BaseXBar::Layer
<SrcType
,DstType
>::drain()
586 //We should check that we're not "doing" anything, and that noone is
587 //waiting. We might be idle but have someone waiting if the device we
588 //contacted for a retry didn't actually retry.
590 DPRINTF(Drain
, "Crossbar not drained\n");
591 return DrainState::Draining
;
593 return DrainState::Drained
;
597 template <typename SrcType
, typename DstType
>
599 BaseXBar::Layer
<SrcType
,DstType
>::regStats()
601 using namespace Stats
;
604 .name(name() + ".occupancy")
605 .desc("Layer occupancy (ticks)")
609 .name(name() + ".utilization")
610 .desc("Layer utilization (%)")
614 utilization
= 100 * occupancy
/ simTicks
;
618 * Crossbar layer template instantiations. Could be removed with _impl.hh
619 * file, but since there are only two given options (MasterPort and
620 * SlavePort) it seems a bit excessive at this point.
622 template class BaseXBar::Layer
<SlavePort
,MasterPort
>;
623 template class BaseXBar::Layer
<MasterPort
,SlavePort
>;