| /* |
| * Copyright (c) 2011-2014 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 "base/misc.hh" |
| #include "base/trace.hh" |
| #include "debug/AddrRanges.hh" |
| #include "debug/CoherentXBar.hh" |
| #include "mem/coherent_xbar.hh" |
| #include "sim/system.hh" |
| |
| CoherentXBar::CoherentXBar(const CoherentXBarParams *p) |
| : BaseXBar(p), system(p->system), snoopFilter(p->snoop_filter) |
| { |
| // create the ports based on the size of the master and slave |
| // vector ports, and the presence of the default port, the ports |
| // are enumerated starting from zero |
| for (int i = 0; i < p->port_master_connection_count; ++i) { |
| std::string portName = csprintf("%s.master[%d]", name(), i); |
| MasterPort* bp = new CoherentXBarMasterPort(portName, *this, i); |
| masterPorts.push_back(bp); |
| reqLayers.push_back(new ReqLayer(*bp, *this, |
| csprintf(".reqLayer%d", i))); |
| snoopLayers.push_back(new SnoopLayer(*bp, *this, |
| csprintf(".snoopLayer%d", i))); |
| } |
| |
| // see if we have a default slave device connected and if so add |
| // our corresponding master port |
| if (p->port_default_connection_count) { |
| defaultPortID = masterPorts.size(); |
| std::string portName = name() + ".default"; |
| MasterPort* bp = new CoherentXBarMasterPort(portName, *this, |
| defaultPortID); |
| masterPorts.push_back(bp); |
| reqLayers.push_back(new ReqLayer(*bp, *this, csprintf(".reqLayer%d", |
| defaultPortID))); |
| snoopLayers.push_back(new SnoopLayer(*bp, *this, |
| csprintf(".snoopLayer%d", |
| defaultPortID))); |
| } |
| |
| // create the slave ports, once again starting at zero |
| for (int i = 0; i < p->port_slave_connection_count; ++i) { |
| std::string portName = csprintf("%s.slave[%d]", name(), i); |
| SlavePort* bp = new CoherentXBarSlavePort(portName, *this, i); |
| slavePorts.push_back(bp); |
| respLayers.push_back(new RespLayer(*bp, *this, |
| csprintf(".respLayer%d", i))); |
| snoopRespPorts.push_back(new SnoopRespPort(*bp, *this)); |
| } |
| |
| if (snoopFilter) |
| snoopFilter->setSlavePorts(slavePorts); |
| |
| clearPortCache(); |
| } |
| |
| CoherentXBar::~CoherentXBar() |
| { |
| for (auto l: reqLayers) |
| delete l; |
| for (auto l: respLayers) |
| delete l; |
| for (auto l: snoopLayers) |
| delete l; |
| for (auto p: snoopRespPorts) |
| delete p; |
| } |
| |
| void |
| CoherentXBar::init() |
| { |
| // the base class is responsible for determining the block size |
| BaseXBar::init(); |
| |
| // iterate over our slave ports and determine which of our |
| // neighbouring master ports are snooping and add them as snoopers |
| for (const auto& p: slavePorts) { |
| // check if the connected master port is snooping |
| if (p->isSnooping()) { |
| DPRINTF(AddrRanges, "Adding snooping master %s\n", |
| p->getMasterPort().name()); |
| snoopPorts.push_back(p); |
| } |
| } |
| |
| if (snoopPorts.empty()) |
| warn("CoherentXBar %s has no snooping ports attached!\n", name()); |
| } |
| |
| bool |
| CoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_id) |
| { |
| // determine the source port based on the id |
| SlavePort *src_port = slavePorts[slave_port_id]; |
| |
| // remember if the packet is an express snoop |
| bool is_express_snoop = pkt->isExpressSnoop(); |
| |
| // determine the destination based on the address |
| PortID master_port_id = findPort(pkt->getAddr()); |
| |
| // test if the crossbar should be considered occupied for the current |
| // port, and exclude express snoops from the check |
| if (!is_express_snoop && !reqLayers[master_port_id]->tryTiming(src_port)) { |
| DPRINTF(CoherentXBar, "recvTimingReq: src %s %s 0x%x BUSY\n", |
| src_port->name(), pkt->cmdString(), pkt->getAddr()); |
| return false; |
| } |
| |
| DPRINTF(CoherentXBar, "recvTimingReq: src %s %s expr %d 0x%x\n", |
| src_port->name(), pkt->cmdString(), is_express_snoop, |
| pkt->getAddr()); |
| |
| // store size and command as they might be modified when |
| // forwarding the packet |
| unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0; |
| unsigned int pkt_cmd = pkt->cmdToIndex(); |
| |
| // set the source port for routing of the response |
| pkt->setSrc(slave_port_id); |
| |
| calcPacketTiming(pkt); |
| Tick packetFinishTime = pkt->lastWordDelay + curTick(); |
| |
| // uncacheable requests need never be snooped |
| if (!pkt->req->isUncacheable() && !system->bypassCaches()) { |
| // the packet is a memory-mapped request and should be |
| // broadcasted to our snoopers but the source |
| if (snoopFilter) { |
| // check with the snoop filter where to forward this packet |
| auto sf_res = snoopFilter->lookupRequest(pkt, *src_port); |
| packetFinishTime += sf_res.second * clockPeriod(); |
| DPRINTF(CoherentXBar, "recvTimingReq: src %s %s 0x%x"\ |
| " SF size: %i lat: %i\n", src_port->name(), |
| pkt->cmdString(), pkt->getAddr(), sf_res.first.size(), |
| sf_res.second); |
| forwardTiming(pkt, slave_port_id, sf_res.first); |
| } else { |
| forwardTiming(pkt, slave_port_id); |
| } |
| } |
| |
| // remember if we add an outstanding req so we can undo it if |
| // necessary, if the packet needs a response, we should add it |
| // as outstanding and express snoops never fail so there is |
| // not need to worry about them |
| bool add_outstanding = !is_express_snoop && pkt->needsResponse(); |
| |
| // keep track that we have an outstanding request packet |
| // matching this request, this is used by the coherency |
| // mechanism in determining what to do with snoop responses |
| // (in recvTimingSnoop) |
| if (add_outstanding) { |
| // we should never have an exsiting request outstanding |
| assert(outstandingReq.find(pkt->req) == outstandingReq.end()); |
| outstandingReq.insert(pkt->req); |
| } |
| |
| // Note: Cannot create a copy of the full packet, here. |
| MemCmd orig_cmd(pkt->cmd); |
| |
| // since it is a normal request, attempt to send the packet |
| bool success = masterPorts[master_port_id]->sendTimingReq(pkt); |
| |
| if (snoopFilter && !pkt->req->isUncacheable() |
| && !system->bypassCaches()) { |
| // The packet may already be overwritten by the sendTimingReq function. |
| // The snoop filter needs to see the original request *and* the return |
| // status of the send operation, so we need to recreate the original |
| // request. Atomic mode does not have the issue, as there the send |
| // operation and the response happen instantaneously and don't need two |
| // phase tracking. |
| MemCmd tmp_cmd(pkt->cmd); |
| pkt->cmd = orig_cmd; |
| // Let the snoop filter know about the success of the send operation |
| snoopFilter->updateRequest(pkt, *src_port, !success); |
| pkt->cmd = tmp_cmd; |
| } |
| |
| // if this is an express snoop, we are done at this point |
| if (is_express_snoop) { |
| assert(success); |
| snoops++; |
| } else { |
| // for normal requests, check if successful |
| if (!success) { |
| // inhibited packets should never be forced to retry |
| assert(!pkt->memInhibitAsserted()); |
| |
| // if it was added as outstanding and the send failed, then |
| // erase it again |
| if (add_outstanding) |
| outstandingReq.erase(pkt->req); |
| |
| // undo the calculation so we can check for 0 again |
| pkt->firstWordDelay = pkt->lastWordDelay = 0; |
| |
| DPRINTF(CoherentXBar, "recvTimingReq: src %s %s 0x%x RETRY\n", |
| src_port->name(), pkt->cmdString(), pkt->getAddr()); |
| |
| // update the layer state and schedule an idle event |
| reqLayers[master_port_id]->failedTiming(src_port, |
| clockEdge(headerCycles)); |
| } else { |
| // update the layer state and schedule an idle event |
| reqLayers[master_port_id]->succeededTiming(packetFinishTime); |
| } |
| } |
| |
| // stats updates only consider packets that were successfully sent |
| if (success) { |
| pktCount[slave_port_id][master_port_id]++; |
| pktSize[slave_port_id][master_port_id] += pkt_size; |
| transDist[pkt_cmd]++; |
| } |
| |
| return success; |
| } |
| |
| bool |
| CoherentXBar::recvTimingResp(PacketPtr pkt, PortID master_port_id) |
| { |
| // determine the source port based on the id |
| MasterPort *src_port = masterPorts[master_port_id]; |
| |
| // determine the destination based on what is stored in the packet |
| PortID slave_port_id = pkt->getDest(); |
| |
| // test if the crossbar should be considered occupied for the |
| // current port |
| if (!respLayers[slave_port_id]->tryTiming(src_port)) { |
| DPRINTF(CoherentXBar, "recvTimingResp: src %s %s 0x%x BUSY\n", |
| src_port->name(), pkt->cmdString(), pkt->getAddr()); |
| return false; |
| } |
| |
| DPRINTF(CoherentXBar, "recvTimingResp: src %s %s 0x%x\n", |
| src_port->name(), pkt->cmdString(), pkt->getAddr()); |
| |
| // store size and command as they might be modified when |
| // forwarding the packet |
| unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0; |
| unsigned int pkt_cmd = pkt->cmdToIndex(); |
| |
| calcPacketTiming(pkt); |
| Tick packetFinishTime = pkt->lastWordDelay + curTick(); |
| |
| // the packet is a normal response to a request that we should |
| // have seen passing through the crossbar |
| assert(outstandingReq.find(pkt->req) != outstandingReq.end()); |
| |
| if (snoopFilter && !pkt->req->isUncacheable() && !system->bypassCaches()) { |
| // let the snoop filter inspect the response and update its state |
| snoopFilter->updateResponse(pkt, *slavePorts[slave_port_id]); |
| } |
| |
| // remove it as outstanding |
| outstandingReq.erase(pkt->req); |
| |
| // send the packet through the destination slave port |
| bool success M5_VAR_USED = slavePorts[slave_port_id]->sendTimingResp(pkt); |
| |
| // currently it is illegal to block responses... can lead to |
| // deadlock |
| assert(success); |
| |
| respLayers[slave_port_id]->succeededTiming(packetFinishTime); |
| |
| // stats updates |
| pktCount[slave_port_id][master_port_id]++; |
| pktSize[slave_port_id][master_port_id] += pkt_size; |
| transDist[pkt_cmd]++; |
| |
| return true; |
| } |
| |
| void |
| CoherentXBar::recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id) |
| { |
| DPRINTF(CoherentXBar, "recvTimingSnoopReq: src %s %s 0x%x\n", |
| masterPorts[master_port_id]->name(), pkt->cmdString(), |
| pkt->getAddr()); |
| |
| // update stats here as we know the forwarding will succeed |
| transDist[pkt->cmdToIndex()]++; |
| snoops++; |
| |
| // we should only see express snoops from caches |
| assert(pkt->isExpressSnoop()); |
| |
| // set the source port for routing of the response |
| pkt->setSrc(master_port_id); |
| |
| if (snoopFilter) { |
| // let the Snoop Filter work its magic and guide probing |
| auto sf_res = snoopFilter->lookupSnoop(pkt); |
| // No timing here: packetFinishTime += sf_res.second * clockPeriod(); |
| DPRINTF(CoherentXBar, "recvTimingSnoopReq: src %s %s 0x%x"\ |
| " SF size: %i lat: %i\n", masterPorts[master_port_id]->name(), |
| pkt->cmdString(), pkt->getAddr(), sf_res.first.size(), |
| sf_res.second); |
| |
| // forward to all snoopers |
| forwardTiming(pkt, InvalidPortID, sf_res.first); |
| } else { |
| forwardTiming(pkt, InvalidPortID); |
| } |
| |
| // a snoop request came from a connected slave device (one of |
| // our master ports), and if it is not coming from the slave |
| // device responsible for the address range something is |
| // wrong, hence there is nothing further to do as the packet |
| // would be going back to where it came from |
| assert(master_port_id == findPort(pkt->getAddr())); |
| } |
| |
| bool |
| CoherentXBar::recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id) |
| { |
| // determine the source port based on the id |
| SlavePort* src_port = slavePorts[slave_port_id]; |
| |
| // get the destination from the packet |
| PortID dest_port_id = pkt->getDest(); |
| |
| // determine if the response is from a snoop request we |
| // created as the result of a normal request (in which case it |
| // should be in the outstandingReq), or if we merely forwarded |
| // someone else's snoop request |
| bool forwardAsSnoop = outstandingReq.find(pkt->req) == |
| outstandingReq.end(); |
| |
| // test if the crossbar should be considered occupied for the |
| // current port, note that the check is bypassed if the response |
| // is being passed on as a normal response since this is occupying |
| // the response layer rather than the snoop response layer |
| if (forwardAsSnoop) { |
| if (!snoopLayers[dest_port_id]->tryTiming(src_port)) { |
| DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x BUSY\n", |
| src_port->name(), pkt->cmdString(), pkt->getAddr()); |
| return false; |
| } |
| } else { |
| // get the master port that mirrors this slave port internally |
| MasterPort* snoop_port = snoopRespPorts[slave_port_id]; |
| if (!respLayers[dest_port_id]->tryTiming(snoop_port)) { |
| DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x BUSY\n", |
| snoop_port->name(), pkt->cmdString(), pkt->getAddr()); |
| return false; |
| } |
| } |
| |
| DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x\n", |
| src_port->name(), pkt->cmdString(), pkt->getAddr()); |
| |
| // store size and command as they might be modified when |
| // forwarding the packet |
| unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0; |
| unsigned int pkt_cmd = pkt->cmdToIndex(); |
| |
| // responses are never express snoops |
| assert(!pkt->isExpressSnoop()); |
| |
| calcPacketTiming(pkt); |
| Tick packetFinishTime = pkt->lastWordDelay + curTick(); |
| |
| // forward it either as a snoop response or a normal response |
| if (forwardAsSnoop) { |
| // this is a snoop response to a snoop request we forwarded, |
| // e.g. coming from the L1 and going to the L2, and it should |
| // be forwarded as a snoop response |
| |
| if (snoopFilter) { |
| // update the probe filter so that it can properly track the line |
| snoopFilter->updateSnoopForward(pkt, *slavePorts[slave_port_id], |
| *masterPorts[dest_port_id]); |
| } |
| |
| bool success M5_VAR_USED = |
| masterPorts[dest_port_id]->sendTimingSnoopResp(pkt); |
| pktCount[slave_port_id][dest_port_id]++; |
| pktSize[slave_port_id][dest_port_id] += pkt_size; |
| assert(success); |
| |
| snoopLayers[dest_port_id]->succeededTiming(packetFinishTime); |
| } else { |
| // we got a snoop response on one of our slave ports, |
| // i.e. from a coherent master connected to the crossbar, and |
| // since we created the snoop request as part of recvTiming, |
| // this should now be a normal response again |
| outstandingReq.erase(pkt->req); |
| |
| // this is a snoop response from a coherent master, with a |
| // destination field set on its way through the crossbar as |
| // request, hence it should never go back to where the snoop |
| // response came from, but instead to where the original |
| // request came from |
| assert(slave_port_id != dest_port_id); |
| |
| if (snoopFilter) { |
| // update the probe filter so that it can properly track the line |
| snoopFilter->updateSnoopResponse(pkt, *slavePorts[slave_port_id], |
| *slavePorts[dest_port_id]); |
| } |
| |
| DPRINTF(CoherentXBar, "recvTimingSnoopResp: src %s %s 0x%x"\ |
| " FWD RESP\n", src_port->name(), pkt->cmdString(), |
| pkt->getAddr()); |
| |
| // as a normal response, it should go back to a master through |
| // one of our slave ports, at this point we are ignoring the |
| // fact that the response layer could be busy and do not touch |
| // its state |
| bool success M5_VAR_USED = |
| slavePorts[dest_port_id]->sendTimingResp(pkt); |
| |
| // @todo Put the response in an internal FIFO and pass it on |
| // to the response layer from there |
| |
| // currently it is illegal to block responses... can lead |
| // to deadlock |
| assert(success); |
| |
| respLayers[dest_port_id]->succeededTiming(packetFinishTime); |
| } |
| |
| // stats updates |
| transDist[pkt_cmd]++; |
| snoops++; |
| |
| return true; |
| } |
| |
| |
| void |
| CoherentXBar::forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id, |
| const std::vector<SlavePort*>& dests) |
| { |
| DPRINTF(CoherentXBar, "%s for %s address %x size %d\n", __func__, |
| pkt->cmdString(), pkt->getAddr(), pkt->getSize()); |
| |
| // snoops should only happen if the system isn't bypassing caches |
| assert(!system->bypassCaches()); |
| |
| unsigned fanout = 0; |
| |
| for (const auto& p: dests) { |
| // we could have gotten this request from a snooping master |
| // (corresponding to our own slave port that is also in |
| // snoopPorts) and should not send it back to where it came |
| // from |
| if (exclude_slave_port_id == InvalidPortID || |
| p->getId() != exclude_slave_port_id) { |
| // cache is not allowed to refuse snoop |
| p->sendTimingSnoopReq(pkt); |
| fanout++; |
| } |
| } |
| |
| // Stats for fanout of this forward operation |
| snoopFanout.sample(fanout); |
| } |
| |
| void |
| CoherentXBar::recvRetry(PortID master_port_id) |
| { |
| // responses and snoop responses never block on forwarding them, |
| // so the retry will always be coming from a port to which we |
| // tried to forward a request |
| reqLayers[master_port_id]->recvRetry(); |
| } |
| |
| Tick |
| CoherentXBar::recvAtomic(PacketPtr pkt, PortID slave_port_id) |
| { |
| DPRINTF(CoherentXBar, "recvAtomic: packet src %s addr 0x%x cmd %s\n", |
| slavePorts[slave_port_id]->name(), pkt->getAddr(), |
| pkt->cmdString()); |
| |
| unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0; |
| unsigned int pkt_cmd = pkt->cmdToIndex(); |
| |
| MemCmd snoop_response_cmd = MemCmd::InvalidCmd; |
| Tick snoop_response_latency = 0; |
| |
| // uncacheable requests need never be snooped |
| if (!pkt->req->isUncacheable() && !system->bypassCaches()) { |
| // forward to all snoopers but the source |
| std::pair<MemCmd, Tick> snoop_result; |
| if (snoopFilter) { |
| // check with the snoop filter where to forward this packet |
| auto sf_res = |
| snoopFilter->lookupRequest(pkt, *slavePorts[slave_port_id]); |
| snoop_response_latency += sf_res.second * clockPeriod(); |
| DPRINTF(CoherentXBar, "%s: src %s %s 0x%x"\ |
| " SF size: %i lat: %i\n", __func__, |
| slavePorts[slave_port_id]->name(), pkt->cmdString(), |
| pkt->getAddr(), sf_res.first.size(), sf_res.second); |
| snoop_result = forwardAtomic(pkt, slave_port_id, InvalidPortID, |
| sf_res.first); |
| } else { |
| snoop_result = forwardAtomic(pkt, slave_port_id); |
| } |
| snoop_response_cmd = snoop_result.first; |
| snoop_response_latency += snoop_result.second; |
| } |
| |
| // even if we had a snoop response, we must continue and also |
| // perform the actual request at the destination |
| PortID master_port_id = findPort(pkt->getAddr()); |
| |
| // stats updates for the request |
| pktCount[slave_port_id][master_port_id]++; |
| pktSize[slave_port_id][master_port_id] += pkt_size; |
| transDist[pkt_cmd]++; |
| |
| // forward the request to the appropriate destination |
| Tick response_latency = masterPorts[master_port_id]->sendAtomic(pkt); |
| |
| // Lower levels have replied, tell the snoop filter |
| if (snoopFilter && !pkt->req->isUncacheable() && !system->bypassCaches() && |
| pkt->isResponse()) { |
| snoopFilter->updateResponse(pkt, *slavePorts[slave_port_id]); |
| } |
| |
| // if we got a response from a snooper, restore it here |
| if (snoop_response_cmd != MemCmd::InvalidCmd) { |
| // no one else should have responded |
| assert(!pkt->isResponse()); |
| pkt->cmd = snoop_response_cmd; |
| response_latency = snoop_response_latency; |
| } |
| |
| // add the response data |
| if (pkt->isResponse()) { |
| pkt_size = pkt->hasData() ? pkt->getSize() : 0; |
| pkt_cmd = pkt->cmdToIndex(); |
| |
| // stats updates |
| pktCount[slave_port_id][master_port_id]++; |
| pktSize[slave_port_id][master_port_id] += pkt_size; |
| transDist[pkt_cmd]++; |
| } |
| |
| // @todo: Not setting first-word time |
| pkt->lastWordDelay = response_latency; |
| return response_latency; |
| } |
| |
| Tick |
| CoherentXBar::recvAtomicSnoop(PacketPtr pkt, PortID master_port_id) |
| { |
| DPRINTF(CoherentXBar, "recvAtomicSnoop: packet src %s addr 0x%x cmd %s\n", |
| masterPorts[master_port_id]->name(), pkt->getAddr(), |
| pkt->cmdString()); |
| |
| // add the request snoop data |
| snoops++; |
| |
| // forward to all snoopers |
| std::pair<MemCmd, Tick> snoop_result; |
| Tick snoop_response_latency = 0; |
| if (snoopFilter) { |
| auto sf_res = snoopFilter->lookupSnoop(pkt); |
| snoop_response_latency += sf_res.second * clockPeriod(); |
| DPRINTF(CoherentXBar, "%s: src %s %s 0x%x SF size: %i lat: %i\n", |
| __func__, masterPorts[master_port_id]->name(), pkt->cmdString(), |
| pkt->getAddr(), sf_res.first.size(), sf_res.second); |
| snoop_result = forwardAtomic(pkt, InvalidPortID, master_port_id, |
| sf_res.first); |
| } else { |
| snoop_result = forwardAtomic(pkt, InvalidPortID); |
| } |
| MemCmd snoop_response_cmd = snoop_result.first; |
| snoop_response_latency += snoop_result.second; |
| |
| if (snoop_response_cmd != MemCmd::InvalidCmd) |
| pkt->cmd = snoop_response_cmd; |
| |
| // add the response snoop data |
| if (pkt->isResponse()) { |
| snoops++; |
| } |
| |
| // @todo: Not setting first-word time |
| pkt->lastWordDelay = snoop_response_latency; |
| return snoop_response_latency; |
| } |
| |
| std::pair<MemCmd, Tick> |
| CoherentXBar::forwardAtomic(PacketPtr pkt, PortID exclude_slave_port_id, |
| PortID source_master_port_id, |
| const std::vector<SlavePort*>& dests) |
| { |
| // the packet may be changed on snoops, record the original |
| // command to enable us to restore it between snoops so that |
| // additional snoops can take place properly |
| MemCmd orig_cmd = pkt->cmd; |
| MemCmd snoop_response_cmd = MemCmd::InvalidCmd; |
| Tick snoop_response_latency = 0; |
| |
| // snoops should only happen if the system isn't bypassing caches |
| assert(!system->bypassCaches()); |
| |
| unsigned fanout = 0; |
| |
| for (const auto& p: dests) { |
| // we could have gotten this request from a snooping master |
| // (corresponding to our own slave port that is also in |
| // snoopPorts) and should not send it back to where it came |
| // from |
| if (exclude_slave_port_id != InvalidPortID && |
| p->getId() == exclude_slave_port_id) |
| continue; |
| |
| Tick latency = p->sendAtomicSnoop(pkt); |
| fanout++; |
| |
| // in contrast to a functional access, we have to keep on |
| // going as all snoopers must be updated even if we get a |
| // response |
| if (!pkt->isResponse()) |
| continue; |
| |
| // response from snoop agent |
| assert(pkt->cmd != orig_cmd); |
| assert(pkt->memInhibitAsserted()); |
| // should only happen once |
| assert(snoop_response_cmd == MemCmd::InvalidCmd); |
| // save response state |
| snoop_response_cmd = pkt->cmd; |
| snoop_response_latency = latency; |
| |
| if (snoopFilter) { |
| // Handle responses by the snoopers and differentiate between |
| // responses to requests from above and snoops from below |
| if (source_master_port_id != InvalidPortID) { |
| // Getting a response for a snoop from below |
| assert(exclude_slave_port_id == InvalidPortID); |
| snoopFilter->updateSnoopForward(pkt, *p, |
| *masterPorts[source_master_port_id]); |
| } else { |
| // Getting a response for a request from above |
| assert(source_master_port_id == InvalidPortID); |
| snoopFilter->updateSnoopResponse(pkt, *p, |
| *slavePorts[exclude_slave_port_id]); |
| } |
| } |
| // restore original packet state for remaining snoopers |
| pkt->cmd = orig_cmd; |
| } |
| |
| // Stats for fanout |
| snoopFanout.sample(fanout); |
| |
| // the packet is restored as part of the loop and any potential |
| // snoop response is part of the returned pair |
| return std::make_pair(snoop_response_cmd, snoop_response_latency); |
| } |
| |
| void |
| CoherentXBar::recvFunctional(PacketPtr pkt, PortID slave_port_id) |
| { |
| if (!pkt->isPrint()) { |
| // don't do DPRINTFs on PrintReq as it clutters up the output |
| DPRINTF(CoherentXBar, |
| "recvFunctional: packet src %s addr 0x%x cmd %s\n", |
| slavePorts[slave_port_id]->name(), pkt->getAddr(), |
| pkt->cmdString()); |
| } |
| |
| // uncacheable requests need never be snooped |
| if (!pkt->req->isUncacheable() && !system->bypassCaches()) { |
| // forward to all snoopers but the source |
| forwardFunctional(pkt, slave_port_id); |
| } |
| |
| // there is no need to continue if the snooping has found what we |
| // were looking for and the packet is already a response |
| if (!pkt->isResponse()) { |
| PortID dest_id = findPort(pkt->getAddr()); |
| |
| masterPorts[dest_id]->sendFunctional(pkt); |
| } |
| } |
| |
| void |
| CoherentXBar::recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id) |
| { |
| if (!pkt->isPrint()) { |
| // don't do DPRINTFs on PrintReq as it clutters up the output |
| DPRINTF(CoherentXBar, |
| "recvFunctionalSnoop: packet src %s addr 0x%x cmd %s\n", |
| masterPorts[master_port_id]->name(), pkt->getAddr(), |
| pkt->cmdString()); |
| } |
| |
| // forward to all snoopers |
| forwardFunctional(pkt, InvalidPortID); |
| } |
| |
| void |
| CoherentXBar::forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id) |
| { |
| // snoops should only happen if the system isn't bypassing caches |
| assert(!system->bypassCaches()); |
| |
| for (const auto& p: snoopPorts) { |
| // we could have gotten this request from a snooping master |
| // (corresponding to our own slave port that is also in |
| // snoopPorts) and should not send it back to where it came |
| // from |
| if (exclude_slave_port_id == InvalidPortID || |
| p->getId() != exclude_slave_port_id) |
| p->sendFunctionalSnoop(pkt); |
| |
| // if we get a response we are done |
| if (pkt->isResponse()) { |
| break; |
| } |
| } |
| } |
| |
| unsigned int |
| CoherentXBar::drain(DrainManager *dm) |
| { |
| // sum up the individual layers |
| unsigned int total = 0; |
| for (auto l: reqLayers) |
| total += l->drain(dm); |
| for (auto l: respLayers) |
| total += l->drain(dm); |
| for (auto l: snoopLayers) |
| total += l->drain(dm); |
| return total; |
| } |
| |
| void |
| CoherentXBar::regStats() |
| { |
| // register the stats of the base class and our layers |
| BaseXBar::regStats(); |
| for (auto l: reqLayers) |
| l->regStats(); |
| for (auto l: respLayers) |
| l->regStats(); |
| for (auto l: snoopLayers) |
| l->regStats(); |
| |
| snoops |
| .name(name() + ".snoops") |
| .desc("Total snoops (count)") |
| ; |
| |
| snoopFanout |
| .init(0, snoopPorts.size(), 1) |
| .name(name() + ".snoop_fanout") |
| .desc("Request fanout histogram") |
| ; |
| } |
| |
| CoherentXBar * |
| CoherentXBarParams::create() |
| { |
| return new CoherentXBar(this); |
| } |
