/* * Copyright (c) 2011-2015, 2018 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. * * Authors: Ali Saidi * Andreas Hansson * William Wang */ /** * @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" BaseXBar::BaseXBar(const BaseXBarParams *p) : MemObject(p), frontendLatency(p->frontend_latency), forwardLatency(p->forward_latency), responseLatency(p->response_latency), width(p->width), gotAddrRanges(p->port_default_connection_count + p->port_master_connection_count, false), gotAllAddrRanges(false), defaultPortID(InvalidPortID), useDefaultRange(p->use_default_range) {} BaseXBar::~BaseXBar() { for (auto m: masterPorts) delete m; for (auto s: slavePorts) delete s; } void BaseXBar::init() { } BaseMasterPort & BaseXBar::getMasterPort(const std::string &if_name, PortID idx) { if (if_name == "master" && idx < masterPorts.size()) { // the master port index translates directly to the vector position return *masterPorts[idx]; } else if (if_name == "default") { return *masterPorts[defaultPortID]; } else { return MemObject::getMasterPort(if_name, idx); } } BaseSlavePort & BaseXBar::getSlavePort(const std::string &if_name, PortID idx) { if (if_name == "slave" && idx < slavePorts.size()) { // the slave port index translates directly to the vector position return *slavePorts[idx]; } else { return MemObject::getSlavePort(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 > SimClock::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(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 BaseXBar::Layer::Layer(DstType& _port, BaseXBar& _xbar, const std::string& _name) : port(_port), xbar(_xbar), _name(_name), state(IDLE), waitingForPeer(NULL), releaseEvent([this]{ releaseLayer(); }, name()) { } template void BaseXBar::Layer::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 bool BaseXBar::Layer::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 slave 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 void BaseXBar::Layer::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 void BaseXBar::Layer::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 void BaseXBar::Layer::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 void BaseXBar::Layer::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 void BaseXBar::Layer::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 slave 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 master_port_id) { DPRINTF(AddrRanges, "Received range change from slave port %s\n", masterPorts[master_port_id]->getSlavePort().name()); // remember that we got a range from this master port and thus the // connected slave module gotAddrRanges[master_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::const_iterator r = gotAddrRanges.begin(); while (gotAllAddrRanges && r != gotAddrRanges.end()) { gotAllAddrRanges &= *r++; } if (gotAllAddrRanges) DPRINTF(AddrRanges, "Got address ranges from all slaves\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 (master_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 = masterPorts[master_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[master_port_id]) { for (auto p = portMap.begin(); p != portMap.end(); ) { if (p->second == master_port_id) // erasing invalidates the iterator, so advance it // before the deletion takes place portMap.erase(p++); else p++; } } AddrRangeList ranges = masterPorts[master_port_id]->getAddrRanges(); for (const auto& r: ranges) { DPRINTF(AddrRanges, "Adding range %s for id %d\n", r.to_string(), master_port_id); if (portMap.insert(r, master_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(), masterPorts[master_port_id]->getSlavePort().name(), masterPorts[conflict_id]->getSlavePort().name()); } } } // if we have received ranges from all our neighbouring slave // modules, go ahead and tell our connected master 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 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 master ports that our address // ranges have changed for (const auto& s: slavePorts) s->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 master 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 Stats; transDist .init(MemCmd::NUM_MEM_CMDS) .name(name() + ".trans_dist") .desc("Transaction distribution") .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(slavePorts.size(), masterPorts.size()) .name(name() + ".pkt_count") .desc("Packet count per connected master and slave (bytes)") .flags(total | nozero | nonan); pktSize .init(slavePorts.size(), masterPorts.size()) .name(name() + ".pkt_size") .desc("Cumulative packet size per connected master and slave (bytes)") .flags(total | nozero | nonan); // both the packet count and total size are two-dimensional // vectors, indexed by slave port id and master port id, thus the // neighbouring master and slave, they do not differentiate what // came from the master and was forwarded to the slave (requests // and snoop responses) and what came from the slave and was // forwarded to the master (responses and snoop requests) for (int i = 0; i < slavePorts.size(); i++) { pktCount.subname(i, slavePorts[i]->getMasterPort().name()); pktSize.subname(i, slavePorts[i]->getMasterPort().name()); for (int j = 0; j < masterPorts.size(); j++) { pktCount.ysubname(j, masterPorts[j]->getSlavePort().name()); pktSize.ysubname(j, masterPorts[j]->getSlavePort().name()); } } } template DrainState BaseXBar::Layer::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; } } template void BaseXBar::Layer::regStats() { using namespace Stats; occupancy .name(name() + ".occupancy") .desc("Layer occupancy (ticks)") .flags(nozero); utilization .name(name() + ".utilization") .desc("Layer utilization (%)") .precision(1) .flags(nozero); utilization = 100 * occupancy / simTicks; } /** * Crossbar layer template instantiations. Could be removed with _impl.hh * file, but since there are only two given options (MasterPort and * SlavePort) it seems a bit excessive at this point. */ template class BaseXBar::Layer; template class BaseXBar::Layer;