| /* |
| * Copyright (c) 2011-2015, 2018-2020 ARM Limited |
| * All rights reserved |
| * |
| * The license below extends only to copyright in the software and shall |
| * not be construed as granting a license to any other intellectual |
| * property including but not limited to intellectual property relating |
| * to a hardware implementation of the functionality of the software |
| * licensed hereunder. You may use the software subject to the license |
| * terms below provided that you ensure that this notice is replicated |
| * unmodified and in its entirety in all distributions of the software, |
| * modified or unmodified, in source code or in binary form. |
| * |
| * Copyright (c) 2006 The Regents of The University of Michigan |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer; |
| * redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution; |
| * neither the name of the copyright holders nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /** |
| * @file |
| * Definition of a crossbar object. |
| */ |
| |
| #include "mem/xbar.hh" |
| |
| #include "base/logging.hh" |
| #include "base/trace.hh" |
| #include "debug/AddrRanges.hh" |
| #include "debug/Drain.hh" |
| #include "debug/XBar.hh" |
| |
| namespace gem5 |
| { |
| |
| BaseXBar::BaseXBar(const BaseXBarParams &p) |
| : ClockedObject(p), |
| frontendLatency(p.frontend_latency), |
| forwardLatency(p.forward_latency), |
| responseLatency(p.response_latency), |
| headerLatency(p.header_latency), |
| width(p.width), |
| gotAddrRanges(p.port_default_connection_count + |
| p.port_mem_side_ports_connection_count, false), |
| gotAllAddrRanges(false), defaultPortID(InvalidPortID), |
| useDefaultRange(p.use_default_range), |
| |
| ADD_STAT(transDist, statistics::units::Count::get(), |
| "Transaction distribution"), |
| ADD_STAT(pktCount, statistics::units::Count::get(), |
| "Packet count per connected requestor and responder"), |
| ADD_STAT(pktSize, statistics::units::Byte::get(), |
| "Cumulative packet size per connected requestor and responder") |
| { |
| } |
| |
| BaseXBar::~BaseXBar() |
| { |
| for (auto port: memSidePorts) |
| delete port; |
| |
| for (auto port: cpuSidePorts) |
| delete port; |
| } |
| |
| Port & |
| BaseXBar::getPort(const std::string &if_name, PortID idx) |
| { |
| if (if_name == "mem_side_ports" && idx < memSidePorts.size()) { |
| // the memory-side ports index translates directly to the vector |
| // position |
| return *memSidePorts[idx]; |
| } else if (if_name == "default") { |
| return *memSidePorts[defaultPortID]; |
| } else if (if_name == "cpu_side_ports" && idx < cpuSidePorts.size()) { |
| // the CPU-side ports index translates directly to the vector position |
| return *cpuSidePorts[idx]; |
| } else { |
| return ClockedObject::getPort(if_name, idx); |
| } |
| } |
| |
| void |
| BaseXBar::calcPacketTiming(PacketPtr pkt, Tick header_delay) |
| { |
| // the crossbar will be called at a time that is not necessarily |
| // coinciding with its own clock, so start by determining how long |
| // until the next clock edge (could be zero) |
| Tick offset = clockEdge() - curTick(); |
| |
| // the header delay depends on the path through the crossbar, and |
| // we therefore rely on the caller to provide the actual |
| // value |
| pkt->headerDelay += offset + header_delay; |
| |
| // note that we add the header delay to the existing value, and |
| // align it to the crossbar clock |
| |
| // do a quick sanity check to ensure the timings are not being |
| // ignored, note that this specific value may cause problems for |
| // slower interconnects |
| panic_if(pkt->headerDelay > sim_clock::as_int::us, |
| "Encountered header delay exceeding 1 us\n"); |
| |
| if (pkt->hasData()) { |
| // the payloadDelay takes into account the relative time to |
| // deliver the payload of the packet, after the header delay, |
| // we take the maximum since the payload delay could already |
| // be longer than what this parcitular crossbar enforces. |
| pkt->payloadDelay = std::max<Tick>(pkt->payloadDelay, |
| divCeil(pkt->getSize(), width) * |
| clockPeriod()); |
| } |
| |
| // the payload delay is not paying for the clock offset as that is |
| // already done using the header delay, and the payload delay is |
| // also used to determine how long the crossbar layer is busy and |
| // thus regulates throughput |
| } |
| |
| template <typename SrcType, typename DstType> |
| BaseXBar::Layer<SrcType, DstType>::Layer(DstType& _port, BaseXBar& _xbar, |
| const std::string& _name) : |
| statistics::Group(&_xbar, _name.c_str()), |
| port(_port), xbar(_xbar), _name(xbar.name() + "." + _name), state(IDLE), |
| waitingForPeer(NULL), releaseEvent([this]{ releaseLayer(); }, name()), |
| ADD_STAT(occupancy, statistics::units::Tick::get(), "Layer occupancy (ticks)"), |
| ADD_STAT(utilization, statistics::units::Ratio::get(), "Layer utilization") |
| { |
| occupancy |
| .flags(statistics::nozero); |
| |
| utilization |
| .precision(1) |
| .flags(statistics::nozero); |
| |
| utilization = occupancy / simTicks; |
| } |
| |
| template <typename SrcType, typename DstType> |
| void BaseXBar::Layer<SrcType, DstType>::occupyLayer(Tick until) |
| { |
| // ensure the state is busy at this point, as the layer should |
| // transition from idle as soon as it has decided to forward the |
| // packet to prevent any follow-on calls to sendTiming seeing an |
| // unoccupied layer |
| assert(state == BUSY); |
| |
| // until should never be 0 as express snoops never occupy the layer |
| assert(until != 0); |
| xbar.schedule(releaseEvent, until); |
| |
| // account for the occupied ticks |
| occupancy += until - curTick(); |
| |
| DPRINTF(BaseXBar, "The crossbar layer is now busy from tick %d to %d\n", |
| curTick(), until); |
| } |
| |
| template <typename SrcType, typename DstType> |
| bool |
| BaseXBar::Layer<SrcType, DstType>::tryTiming(SrcType* src_port) |
| { |
| // if we are in the retry state, we will not see anything but the |
| // retrying port (or in the case of the snoop ports the snoop |
| // response port that mirrors the actual CPU-side port) as we leave |
| // this state again in zero time if the peer does not immediately |
| // call the layer when receiving the retry |
| |
| // first we see if the layer is busy, next we check if the |
| // destination port is already engaged in a transaction waiting |
| // for a retry from the peer |
| if (state == BUSY || waitingForPeer != NULL) { |
| // the port should not be waiting already |
| assert(std::find(waitingForLayer.begin(), waitingForLayer.end(), |
| src_port) == waitingForLayer.end()); |
| |
| // put the port at the end of the retry list waiting for the |
| // layer to be freed up (and in the case of a busy peer, for |
| // that transaction to go through, and then the layer to free |
| // up) |
| waitingForLayer.push_back(src_port); |
| return false; |
| } |
| |
| state = BUSY; |
| |
| return true; |
| } |
| |
| template <typename SrcType, typename DstType> |
| void |
| BaseXBar::Layer<SrcType, DstType>::succeededTiming(Tick busy_time) |
| { |
| // we should have gone from idle or retry to busy in the tryTiming |
| // test |
| assert(state == BUSY); |
| |
| // occupy the layer accordingly |
| occupyLayer(busy_time); |
| } |
| |
| template <typename SrcType, typename DstType> |
| void |
| BaseXBar::Layer<SrcType, DstType>::failedTiming(SrcType* src_port, |
| Tick busy_time) |
| { |
| // ensure no one got in between and tried to send something to |
| // this port |
| assert(waitingForPeer == NULL); |
| |
| // if the source port is the current retrying one or not, we have |
| // failed in forwarding and should track that we are now waiting |
| // for the peer to send a retry |
| waitingForPeer = src_port; |
| |
| // we should have gone from idle or retry to busy in the tryTiming |
| // test |
| assert(state == BUSY); |
| |
| // occupy the bus accordingly |
| occupyLayer(busy_time); |
| } |
| |
| template <typename SrcType, typename DstType> |
| void |
| BaseXBar::Layer<SrcType, DstType>::releaseLayer() |
| { |
| // releasing the bus means we should now be idle |
| assert(state == BUSY); |
| assert(!releaseEvent.scheduled()); |
| |
| // update the state |
| state = IDLE; |
| |
| // bus layer is now idle, so if someone is waiting we can retry |
| if (!waitingForLayer.empty()) { |
| // there is no point in sending a retry if someone is still |
| // waiting for the peer |
| if (waitingForPeer == NULL) |
| retryWaiting(); |
| } else if (waitingForPeer == NULL && drainState() == DrainState::Draining) { |
| DPRINTF(Drain, "Crossbar done draining, signaling drain manager\n"); |
| //If we weren't able to drain before, do it now. |
| signalDrainDone(); |
| } |
| } |
| |
| template <typename SrcType, typename DstType> |
| void |
| BaseXBar::Layer<SrcType, DstType>::retryWaiting() |
| { |
| // this should never be called with no one waiting |
| assert(!waitingForLayer.empty()); |
| |
| // we always go to retrying from idle |
| assert(state == IDLE); |
| |
| // update the state |
| state = RETRY; |
| |
| // set the retrying port to the front of the retry list and pop it |
| // off the list |
| SrcType* retryingPort = waitingForLayer.front(); |
| waitingForLayer.pop_front(); |
| |
| // tell the port to retry, which in some cases ends up calling the |
| // layer again |
| sendRetry(retryingPort); |
| |
| // If the layer is still in the retry state, sendTiming wasn't |
| // called in zero time (e.g. the cache does this when a writeback |
| // is squashed) |
| if (state == RETRY) { |
| // update the state to busy and reset the retrying port, we |
| // have done our bit and sent the retry |
| state = BUSY; |
| |
| // occupy the crossbar layer until the next clock edge |
| occupyLayer(xbar.clockEdge()); |
| } |
| } |
| |
| template <typename SrcType, typename DstType> |
| void |
| BaseXBar::Layer<SrcType, DstType>::recvRetry() |
| { |
| // we should never get a retry without having failed to forward |
| // something to this port |
| assert(waitingForPeer != NULL); |
| |
| // add the port where the failed packet originated to the front of |
| // the waiting ports for the layer, this allows us to call retry |
| // on the port immediately if the crossbar layer is idle |
| waitingForLayer.push_front(waitingForPeer); |
| |
| // we are no longer waiting for the peer |
| waitingForPeer = NULL; |
| |
| // if the layer is idle, retry this port straight away, if we |
| // are busy, then simply let the port wait for its turn |
| if (state == IDLE) { |
| retryWaiting(); |
| } else { |
| assert(state == BUSY); |
| } |
| } |
| |
| PortID |
| BaseXBar::findPort(AddrRange addr_range) |
| { |
| // we should never see any address lookups before we've got the |
| // ranges of all connected CPU-side-port modules |
| assert(gotAllAddrRanges); |
| |
| // Check the address map interval tree |
| auto i = portMap.contains(addr_range); |
| if (i != portMap.end()) { |
| return i->second; |
| } |
| |
| // Check if this matches the default range |
| if (useDefaultRange) { |
| if (addr_range.isSubset(defaultRange)) { |
| DPRINTF(AddrRanges, " found addr %s on default\n", |
| addr_range.to_string()); |
| return defaultPortID; |
| } |
| } else if (defaultPortID != InvalidPortID) { |
| DPRINTF(AddrRanges, "Unable to find destination for %s, " |
| "will use default port\n", addr_range.to_string()); |
| return defaultPortID; |
| } |
| |
| // we should use the range for the default port and it did not |
| // match, or the default port is not set |
| fatal("Unable to find destination for %s on %s\n", addr_range.to_string(), |
| name()); |
| } |
| |
| /** Function called by the port when the crossbar is receiving a range change.*/ |
| void |
| BaseXBar::recvRangeChange(PortID mem_side_port_id) |
| { |
| DPRINTF(AddrRanges, "Received range change from cpu_side_ports %s\n", |
| memSidePorts[mem_side_port_id]->getPeer()); |
| |
| // remember that we got a range from this memory-side port and thus the |
| // connected CPU-side-port module |
| gotAddrRanges[mem_side_port_id] = true; |
| |
| // update the global flag |
| if (!gotAllAddrRanges) { |
| // take a logical AND of all the ports and see if we got |
| // ranges from everyone |
| gotAllAddrRanges = true; |
| std::vector<bool>::const_iterator r = gotAddrRanges.begin(); |
| while (gotAllAddrRanges && r != gotAddrRanges.end()) { |
| gotAllAddrRanges &= *r++; |
| } |
| if (gotAllAddrRanges) |
| DPRINTF(AddrRanges, "Got address ranges from all responders\n"); |
| } |
| |
| // note that we could get the range from the default port at any |
| // point in time, and we cannot assume that the default range is |
| // set before the other ones are, so we do additional checks once |
| // all ranges are provided |
| if (mem_side_port_id == defaultPortID) { |
| // only update if we are indeed checking ranges for the |
| // default port since the port might not have a valid range |
| // otherwise |
| if (useDefaultRange) { |
| AddrRangeList ranges = memSidePorts[mem_side_port_id]-> |
| getAddrRanges(); |
| |
| if (ranges.size() != 1) |
| fatal("Crossbar %s may only have a single default range", |
| name()); |
| |
| defaultRange = ranges.front(); |
| } |
| } else { |
| // the ports are allowed to update their address ranges |
| // dynamically, so remove any existing entries |
| if (gotAddrRanges[mem_side_port_id]) { |
| for (auto p = portMap.begin(); p != portMap.end(); ) { |
| if (p->second == mem_side_port_id) |
| // erasing invalidates the iterator, so advance it |
| // before the deletion takes place |
| portMap.erase(p++); |
| else |
| p++; |
| } |
| } |
| |
| AddrRangeList ranges = memSidePorts[mem_side_port_id]-> |
| getAddrRanges(); |
| |
| for (const auto& r: ranges) { |
| DPRINTF(AddrRanges, "Adding range %s for id %d\n", |
| r.to_string(), mem_side_port_id); |
| if (portMap.insert(r, mem_side_port_id) == portMap.end()) { |
| PortID conflict_id = portMap.intersects(r)->second; |
| fatal("%s has two ports responding within range " |
| "%s:\n\t%s\n\t%s\n", |
| name(), |
| r.to_string(), |
| memSidePorts[mem_side_port_id]->getPeer(), |
| memSidePorts[conflict_id]->getPeer()); |
| } |
| } |
| } |
| |
| // if we have received ranges from all our neighbouring CPU-side-port |
| // modules, go ahead and tell our connected memory-side-port modules in |
| // turn, this effectively assumes a tree structure of the system |
| if (gotAllAddrRanges) { |
| DPRINTF(AddrRanges, "Aggregating address ranges\n"); |
| xbarRanges.clear(); |
| |
| // start out with the default range |
| if (useDefaultRange) { |
| if (!gotAddrRanges[defaultPortID]) |
| fatal("Crossbar %s uses default range, but none provided", |
| name()); |
| |
| xbarRanges.push_back(defaultRange); |
| DPRINTF(AddrRanges, "-- Adding default %s\n", |
| defaultRange.to_string()); |
| } |
| |
| // merge all interleaved ranges and add any range that is not |
| // a subset of the default range |
| std::vector<AddrRange> intlv_ranges; |
| for (const auto& r: portMap) { |
| // if the range is interleaved then save it for now |
| if (r.first.interleaved()) { |
| // if we already got interleaved ranges that are not |
| // part of the same range, then first do a merge |
| // before we add the new one |
| if (!intlv_ranges.empty() && |
| !intlv_ranges.back().mergesWith(r.first)) { |
| DPRINTF(AddrRanges, "-- Merging range from %d ranges\n", |
| intlv_ranges.size()); |
| AddrRange merged_range(intlv_ranges); |
| // next decide if we keep the merged range or not |
| if (!(useDefaultRange && |
| merged_range.isSubset(defaultRange))) { |
| xbarRanges.push_back(merged_range); |
| DPRINTF(AddrRanges, "-- Adding merged range %s\n", |
| merged_range.to_string()); |
| } |
| intlv_ranges.clear(); |
| } |
| intlv_ranges.push_back(r.first); |
| } else { |
| // keep the current range if not a subset of the default |
| if (!(useDefaultRange && |
| r.first.isSubset(defaultRange))) { |
| xbarRanges.push_back(r.first); |
| DPRINTF(AddrRanges, "-- Adding range %s\n", |
| r.first.to_string()); |
| } |
| } |
| } |
| |
| // if there is still interleaved ranges waiting to be merged, |
| // go ahead and do it |
| if (!intlv_ranges.empty()) { |
| DPRINTF(AddrRanges, "-- Merging range from %d ranges\n", |
| intlv_ranges.size()); |
| AddrRange merged_range(intlv_ranges); |
| if (!(useDefaultRange && merged_range.isSubset(defaultRange))) { |
| xbarRanges.push_back(merged_range); |
| DPRINTF(AddrRanges, "-- Adding merged range %s\n", |
| merged_range.to_string()); |
| } |
| } |
| |
| // also check that no range partially intersects with the |
| // default range, this has to be done after all ranges are set |
| // as there are no guarantees for when the default range is |
| // update with respect to the other ones |
| if (useDefaultRange) { |
| for (const auto& r: xbarRanges) { |
| // see if the new range is partially |
| // overlapping the default range |
| if (r.intersects(defaultRange) && |
| !r.isSubset(defaultRange)) |
| fatal("Range %s intersects the " \ |
| "default range of %s but is not a " \ |
| "subset\n", r.to_string(), name()); |
| } |
| } |
| |
| // tell all our neighbouring memory-side ports that our address |
| // ranges have changed |
| for (const auto& port: cpuSidePorts) |
| port->sendRangeChange(); |
| } |
| } |
| |
| AddrRangeList |
| BaseXBar::getAddrRanges() const |
| { |
| // we should never be asked without first having sent a range |
| // change, and the latter is only done once we have all the ranges |
| // of the connected devices |
| assert(gotAllAddrRanges); |
| |
| // at the moment, this never happens, as there are no cycles in |
| // the range queries and no devices on the memory side of a crossbar |
| // (CPU, cache, bridge etc) actually care about the ranges of the |
| // ports they are connected to |
| |
| DPRINTF(AddrRanges, "Received address range request\n"); |
| |
| return xbarRanges; |
| } |
| |
| void |
| BaseXBar::regStats() |
| { |
| ClockedObject::regStats(); |
| |
| using namespace statistics; |
| |
| transDist |
| .init(MemCmd::NUM_MEM_CMDS) |
| .flags(nozero); |
| |
| // get the string representation of the commands |
| for (int i = 0; i < MemCmd::NUM_MEM_CMDS; i++) { |
| MemCmd cmd(i); |
| const std::string &cstr = cmd.toString(); |
| transDist.subname(i, cstr); |
| } |
| |
| pktCount |
| .init(cpuSidePorts.size(), memSidePorts.size()) |
| .flags(total | nozero | nonan); |
| |
| pktSize |
| .init(cpuSidePorts.size(), memSidePorts.size()) |
| .flags(total | nozero | nonan); |
| |
| // both the packet count and total size are two-dimensional |
| // vectors, indexed by CPU-side port id and memory-side port id, thus the |
| // neighbouring memory-side ports and CPU-side ports, they do not |
| // differentiate what came from the memory-side ports and was forwarded to |
| // the CPU-side ports (requests and snoop responses) and what came from |
| // the CPU-side ports and was forwarded to the memory-side ports (responses |
| // and snoop requests) |
| for (int i = 0; i < cpuSidePorts.size(); i++) { |
| pktCount.subname(i, cpuSidePorts[i]->getPeer().name()); |
| pktSize.subname(i, cpuSidePorts[i]->getPeer().name()); |
| for (int j = 0; j < memSidePorts.size(); j++) { |
| pktCount.ysubname(j, memSidePorts[j]->getPeer().name()); |
| pktSize.ysubname(j, memSidePorts[j]->getPeer().name()); |
| } |
| } |
| } |
| |
| template <typename SrcType, typename DstType> |
| DrainState |
| BaseXBar::Layer<SrcType, DstType>::drain() |
| { |
| //We should check that we're not "doing" anything, and that noone is |
| //waiting. We might be idle but have someone waiting if the device we |
| //contacted for a retry didn't actually retry. |
| if (state != IDLE) { |
| DPRINTF(Drain, "Crossbar not drained\n"); |
| return DrainState::Draining; |
| } else { |
| return DrainState::Drained; |
| } |
| } |
| |
| /** |
| * Crossbar layer template instantiations. Could be removed with _impl.hh |
| * file, but since there are only two given options (RequestPort and |
| * ResponsePort) it seems a bit excessive at this point. |
| */ |
| template class BaseXBar::Layer<ResponsePort, RequestPort>; |
| template class BaseXBar::Layer<RequestPort, ResponsePort>; |
| |
| } // namespace gem5 |
