xbar.cc revision 12084:5a3769ff3d55
1/*
2 * Copyright (c) 2011-2015 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
9 * licensed hereunder.  You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2006 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Ali Saidi
41 *          Andreas Hansson
42 *          William Wang
43 */
44
45/**
46 * @file
47 * Definition of a crossbar object.
48 */
49
50#include "mem/xbar.hh"
51
52#include "base/misc.hh"
53#include "base/trace.hh"
54#include "debug/AddrRanges.hh"
55#include "debug/Drain.hh"
56#include "debug/XBar.hh"
57
58BaseXBar::BaseXBar(const BaseXBarParams *p)
59    : MemObject(p),
60      frontendLatency(p->frontend_latency),
61      forwardLatency(p->forward_latency),
62      responseLatency(p->response_latency),
63      width(p->width),
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)
68{}
69
70BaseXBar::~BaseXBar()
71{
72    for (auto m: masterPorts)
73        delete m;
74
75    for (auto s: slavePorts)
76        delete s;
77}
78
79void
80BaseXBar::init()
81{
82}
83
84BaseMasterPort &
85BaseXBar::getMasterPort(const std::string &if_name, PortID idx)
86{
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];
92    } else {
93        return MemObject::getMasterPort(if_name, idx);
94    }
95}
96
97BaseSlavePort &
98BaseXBar::getSlavePort(const std::string &if_name, PortID idx)
99{
100    if (if_name == "slave" && idx < slavePorts.size()) {
101        // the slave port index translates directly to the vector position
102        return *slavePorts[idx];
103    } else {
104        return MemObject::getSlavePort(if_name, idx);
105    }
106}
107
108void
109BaseXBar::calcPacketTiming(PacketPtr pkt, Tick header_delay)
110{
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();
115
116    // the header delay depends on the path through the crossbar, and
117    // we therefore rely on the caller to provide the actual
118    // value
119    pkt->headerDelay += offset + header_delay;
120
121    // note that we add the header delay to the existing value, and
122    // align it to the crossbar clock
123
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");
129
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) *
137                                           clockPeriod());
138    }
139
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
144}
145
146template <typename SrcType, typename DstType>
147BaseXBar::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())
151{
152}
153
154template <typename SrcType, typename DstType>
155void BaseXBar::Layer<SrcType,DstType>::occupyLayer(Tick until)
156{
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
160    // unoccupied layer
161    assert(state == BUSY);
162
163    // until should never be 0 as express snoops never occupy the layer
164    assert(until != 0);
165    xbar.schedule(releaseEvent, until);
166
167    // account for the occupied ticks
168    occupancy += until - curTick();
169
170    DPRINTF(BaseXBar, "The crossbar layer is now busy from tick %d to %d\n",
171            curTick(), until);
172}
173
174template <typename SrcType, typename DstType>
175bool
176BaseXBar::Layer<SrcType,DstType>::tryTiming(SrcType* src_port)
177{
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
183
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());
191
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
195        // up)
196        waitingForLayer.push_back(src_port);
197        return false;
198    }
199
200    state = BUSY;
201
202    return true;
203}
204
205template <typename SrcType, typename DstType>
206void
207BaseXBar::Layer<SrcType,DstType>::succeededTiming(Tick busy_time)
208{
209    // we should have gone from idle or retry to busy in the tryTiming
210    // test
211    assert(state == BUSY);
212
213    // occupy the layer accordingly
214    occupyLayer(busy_time);
215}
216
217template <typename SrcType, typename DstType>
218void
219BaseXBar::Layer<SrcType,DstType>::failedTiming(SrcType* src_port,
220                                              Tick busy_time)
221{
222    // ensure no one got in between and tried to send something to
223    // this port
224    assert(waitingForPeer == NULL);
225
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;
230
231    // we should have gone from idle or retry to busy in the tryTiming
232    // test
233    assert(state == BUSY);
234
235    // occupy the bus accordingly
236    occupyLayer(busy_time);
237}
238
239template <typename SrcType, typename DstType>
240void
241BaseXBar::Layer<SrcType,DstType>::releaseLayer()
242{
243    // releasing the bus means we should now be idle
244    assert(state == BUSY);
245    assert(!releaseEvent.scheduled());
246
247    // update the state
248    state = IDLE;
249
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)
255            retryWaiting();
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.
259        signalDrainDone();
260    }
261}
262
263template <typename SrcType, typename DstType>
264void
265BaseXBar::Layer<SrcType,DstType>::retryWaiting()
266{
267    // this should never be called with no one waiting
268    assert(!waitingForLayer.empty());
269
270    // we always go to retrying from idle
271    assert(state == IDLE);
272
273    // update the state
274    state = RETRY;
275
276    // set the retrying port to the front of the retry list and pop it
277    // off the list
278    SrcType* retryingPort = waitingForLayer.front();
279    waitingForLayer.pop_front();
280
281    // tell the port to retry, which in some cases ends up calling the
282    // layer again
283    sendRetry(retryingPort);
284
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
287    // is squashed)
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
291        state = BUSY;
292
293        // occupy the crossbar layer until the next clock edge
294        occupyLayer(xbar.clockEdge());
295    }
296}
297
298template <typename SrcType, typename DstType>
299void
300BaseXBar::Layer<SrcType,DstType>::recvRetry()
301{
302    // we should never get a retry without having failed to forward
303    // something to this port
304    assert(waitingForPeer != NULL);
305
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);
310
311    // we are no longer waiting for the peer
312    waitingForPeer = NULL;
313
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
316    if (state == IDLE) {
317        retryWaiting();
318    } else {
319        assert(state == BUSY);
320    }
321}
322
323PortID
324BaseXBar::findPort(Addr addr)
325{
326    // we should never see any address lookups before we've got the
327    // ranges of all connected slave modules
328    assert(gotAllAddrRanges);
329
330    // Check the cache
331    PortID dest_id = checkPortCache(addr);
332    if (dest_id != InvalidPortID)
333        return dest_id;
334
335    // Check the address map interval tree
336    auto i = portMap.find(addr);
337    if (i != portMap.end()) {
338        dest_id = i->second;
339        updatePortCache(dest_id, i->first);
340        return dest_id;
341    }
342
343    // Check if this matches the default range
344    if (useDefaultRange) {
345        if (defaultRange.contains(addr)) {
346            DPRINTF(AddrRanges, "  found addr %#llx on default\n",
347                    addr);
348            return defaultPortID;
349        }
350    } else if (defaultPortID != InvalidPortID) {
351        DPRINTF(AddrRanges, "Unable to find destination for addr %#llx, "
352                "will use default port\n", addr);
353        return defaultPortID;
354    }
355
356    // we should use the range for the default port and it did not
357    // match, or the default port is not set
358    fatal("Unable to find destination for addr %#llx on %s\n", addr,
359          name());
360}
361
362/** Function called by the port when the crossbar is receiving a range change.*/
363void
364BaseXBar::recvRangeChange(PortID master_port_id)
365{
366    DPRINTF(AddrRanges, "Received range change from slave port %s\n",
367            masterPorts[master_port_id]->getSlavePort().name());
368
369    // remember that we got a range from this master port and thus the
370    // connected slave module
371    gotAddrRanges[master_port_id] = true;
372
373    // update the global flag
374    if (!gotAllAddrRanges) {
375        // take a logical AND of all the ports and see if we got
376        // ranges from everyone
377        gotAllAddrRanges = true;
378        std::vector<bool>::const_iterator r = gotAddrRanges.begin();
379        while (gotAllAddrRanges &&  r != gotAddrRanges.end()) {
380            gotAllAddrRanges &= *r++;
381        }
382        if (gotAllAddrRanges)
383            DPRINTF(AddrRanges, "Got address ranges from all slaves\n");
384    }
385
386    // note that we could get the range from the default port at any
387    // point in time, and we cannot assume that the default range is
388    // set before the other ones are, so we do additional checks once
389    // all ranges are provided
390    if (master_port_id == defaultPortID) {
391        // only update if we are indeed checking ranges for the
392        // default port since the port might not have a valid range
393        // otherwise
394        if (useDefaultRange) {
395            AddrRangeList ranges = masterPorts[master_port_id]->getAddrRanges();
396
397            if (ranges.size() != 1)
398                fatal("Crossbar %s may only have a single default range",
399                      name());
400
401            defaultRange = ranges.front();
402        }
403    } else {
404        // the ports are allowed to update their address ranges
405        // dynamically, so remove any existing entries
406        if (gotAddrRanges[master_port_id]) {
407            for (auto p = portMap.begin(); p != portMap.end(); ) {
408                if (p->second == master_port_id)
409                    // erasing invalidates the iterator, so advance it
410                    // before the deletion takes place
411                    portMap.erase(p++);
412                else
413                    p++;
414            }
415        }
416
417        AddrRangeList ranges = masterPorts[master_port_id]->getAddrRanges();
418
419        for (const auto& r: ranges) {
420            DPRINTF(AddrRanges, "Adding range %s for id %d\n",
421                    r.to_string(), master_port_id);
422            if (portMap.insert(r, master_port_id) == portMap.end()) {
423                PortID conflict_id = portMap.find(r)->second;
424                fatal("%s has two ports responding within range %s:\n\t%s\n\t%s\n",
425                      name(),
426                      r.to_string(),
427                      masterPorts[master_port_id]->getSlavePort().name(),
428                      masterPorts[conflict_id]->getSlavePort().name());
429            }
430        }
431    }
432
433    // if we have received ranges from all our neighbouring slave
434    // modules, go ahead and tell our connected master modules in
435    // turn, this effectively assumes a tree structure of the system
436    if (gotAllAddrRanges) {
437        DPRINTF(AddrRanges, "Aggregating address ranges\n");
438        xbarRanges.clear();
439
440        // start out with the default range
441        if (useDefaultRange) {
442            if (!gotAddrRanges[defaultPortID])
443                fatal("Crossbar %s uses default range, but none provided",
444                      name());
445
446            xbarRanges.push_back(defaultRange);
447            DPRINTF(AddrRanges, "-- Adding default %s\n",
448                    defaultRange.to_string());
449        }
450
451        // merge all interleaved ranges and add any range that is not
452        // a subset of the default range
453        std::vector<AddrRange> intlv_ranges;
454        for (const auto& r: portMap) {
455            // if the range is interleaved then save it for now
456            if (r.first.interleaved()) {
457                // if we already got interleaved ranges that are not
458                // part of the same range, then first do a merge
459                // before we add the new one
460                if (!intlv_ranges.empty() &&
461                    !intlv_ranges.back().mergesWith(r.first)) {
462                    DPRINTF(AddrRanges, "-- Merging range from %d ranges\n",
463                            intlv_ranges.size());
464                    AddrRange merged_range(intlv_ranges);
465                    // next decide if we keep the merged range or not
466                    if (!(useDefaultRange &&
467                          merged_range.isSubset(defaultRange))) {
468                        xbarRanges.push_back(merged_range);
469                        DPRINTF(AddrRanges, "-- Adding merged range %s\n",
470                                merged_range.to_string());
471                    }
472                    intlv_ranges.clear();
473                }
474                intlv_ranges.push_back(r.first);
475            } else {
476                // keep the current range if not a subset of the default
477                if (!(useDefaultRange &&
478                      r.first.isSubset(defaultRange))) {
479                    xbarRanges.push_back(r.first);
480                    DPRINTF(AddrRanges, "-- Adding range %s\n",
481                            r.first.to_string());
482                }
483            }
484        }
485
486        // if there is still interleaved ranges waiting to be merged,
487        // go ahead and do it
488        if (!intlv_ranges.empty()) {
489            DPRINTF(AddrRanges, "-- Merging range from %d ranges\n",
490                    intlv_ranges.size());
491            AddrRange merged_range(intlv_ranges);
492            if (!(useDefaultRange && merged_range.isSubset(defaultRange))) {
493                xbarRanges.push_back(merged_range);
494                DPRINTF(AddrRanges, "-- Adding merged range %s\n",
495                        merged_range.to_string());
496            }
497        }
498
499        // also check that no range partially overlaps with the
500        // default range, this has to be done after all ranges are set
501        // as there are no guarantees for when the default range is
502        // update with respect to the other ones
503        if (useDefaultRange) {
504            for (const auto& r: xbarRanges) {
505                // see if the new range is partially
506                // overlapping the default range
507                if (r.intersects(defaultRange) &&
508                    !r.isSubset(defaultRange))
509                    fatal("Range %s intersects the "                    \
510                          "default range of %s but is not a "           \
511                          "subset\n", r.to_string(), name());
512            }
513        }
514
515        // tell all our neighbouring master ports that our address
516        // ranges have changed
517        for (const auto& s: slavePorts)
518            s->sendRangeChange();
519    }
520
521    clearPortCache();
522}
523
524AddrRangeList
525BaseXBar::getAddrRanges() const
526{
527    // we should never be asked without first having sent a range
528    // change, and the latter is only done once we have all the ranges
529    // of the connected devices
530    assert(gotAllAddrRanges);
531
532    // at the moment, this never happens, as there are no cycles in
533    // the range queries and no devices on the master side of a crossbar
534    // (CPU, cache, bridge etc) actually care about the ranges of the
535    // ports they are connected to
536
537    DPRINTF(AddrRanges, "Received address range request\n");
538
539    return xbarRanges;
540}
541
542void
543BaseXBar::regStats()
544{
545    ClockedObject::regStats();
546
547    using namespace Stats;
548
549    transDist
550        .init(MemCmd::NUM_MEM_CMDS)
551        .name(name() + ".trans_dist")
552        .desc("Transaction distribution")
553        .flags(nozero);
554
555    // get the string representation of the commands
556    for (int i = 0; i < MemCmd::NUM_MEM_CMDS; i++) {
557        MemCmd cmd(i);
558        const std::string &cstr = cmd.toString();
559        transDist.subname(i, cstr);
560    }
561
562    pktCount
563        .init(slavePorts.size(), masterPorts.size())
564        .name(name() + ".pkt_count")
565        .desc("Packet count per connected master and slave (bytes)")
566        .flags(total | nozero | nonan);
567
568    pktSize
569        .init(slavePorts.size(), masterPorts.size())
570        .name(name() + ".pkt_size")
571        .desc("Cumulative packet size per connected master and slave (bytes)")
572        .flags(total | nozero | nonan);
573
574    // both the packet count and total size are two-dimensional
575    // vectors, indexed by slave port id and master port id, thus the
576    // neighbouring master and slave, they do not differentiate what
577    // came from the master and was forwarded to the slave (requests
578    // and snoop responses) and what came from the slave and was
579    // forwarded to the master (responses and snoop requests)
580    for (int i = 0; i < slavePorts.size(); i++) {
581        pktCount.subname(i, slavePorts[i]->getMasterPort().name());
582        pktSize.subname(i, slavePorts[i]->getMasterPort().name());
583        for (int j = 0; j < masterPorts.size(); j++) {
584            pktCount.ysubname(j, masterPorts[j]->getSlavePort().name());
585            pktSize.ysubname(j, masterPorts[j]->getSlavePort().name());
586        }
587    }
588}
589
590template <typename SrcType, typename DstType>
591DrainState
592BaseXBar::Layer<SrcType,DstType>::drain()
593{
594    //We should check that we're not "doing" anything, and that noone is
595    //waiting. We might be idle but have someone waiting if the device we
596    //contacted for a retry didn't actually retry.
597    if (state != IDLE) {
598        DPRINTF(Drain, "Crossbar not drained\n");
599        return DrainState::Draining;
600    } else {
601        return DrainState::Drained;
602    }
603}
604
605template <typename SrcType, typename DstType>
606void
607BaseXBar::Layer<SrcType,DstType>::regStats()
608{
609    using namespace Stats;
610
611    occupancy
612        .name(name() + ".occupancy")
613        .desc("Layer occupancy (ticks)")
614        .flags(nozero);
615
616    utilization
617        .name(name() + ".utilization")
618        .desc("Layer utilization (%)")
619        .precision(1)
620        .flags(nozero);
621
622    utilization = 100 * occupancy / simTicks;
623}
624
625/**
626 * Crossbar layer template instantiations. Could be removed with _impl.hh
627 * file, but since there are only two given options (MasterPort and
628 * SlavePort) it seems a bit excessive at this point.
629 */
630template class BaseXBar::Layer<SlavePort,MasterPort>;
631template class BaseXBar::Layer<MasterPort,SlavePort>;
632