| /* |
| * Copyright (c) 2011-2013 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 |
| * Copyright (c) 2015 The University of Bologna |
| * 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 |
| * Implementation of the SerialLink Class, modeling Hybrid-Memory-Cube's |
| * serial interface. |
| */ |
| |
| #include "mem/serial_link.hh" |
| |
| #include "base/trace.hh" |
| #include "debug/SerialLink.hh" |
| #include "params/SerialLink.hh" |
| |
| namespace gem5 |
| { |
| |
| SerialLink::SerialLinkResponsePort:: |
| SerialLinkResponsePort(const std::string& _name, |
| SerialLink& _serial_link, |
| SerialLinkRequestPort& _mem_side_port, |
| Cycles _delay, int _resp_limit, |
| const std::vector<AddrRange>& |
| _ranges) |
| : ResponsePort(_name, &_serial_link), serial_link(_serial_link), |
| mem_side_port(_mem_side_port), delay(_delay), |
| ranges(_ranges.begin(), _ranges.end()), |
| outstandingResponses(0), retryReq(false), |
| respQueueLimit(_resp_limit), |
| sendEvent([this]{ trySendTiming(); }, _name) |
| { |
| } |
| |
| SerialLink::SerialLinkRequestPort::SerialLinkRequestPort(const std::string& |
| _name, SerialLink& _serial_link, |
| SerialLinkResponsePort& |
| _cpu_side_port, Cycles _delay, |
| int _req_limit) |
| : RequestPort(_name, &_serial_link), serial_link(_serial_link), |
| cpu_side_port(_cpu_side_port), delay(_delay), reqQueueLimit(_req_limit), |
| sendEvent([this]{ trySendTiming(); }, _name) |
| { |
| } |
| |
| SerialLink::SerialLink(const SerialLinkParams &p) |
| : ClockedObject(p), |
| cpu_side_port(p.name + ".cpu_side_port", *this, mem_side_port, |
| ticksToCycles(p.delay), p.resp_size, p.ranges), |
| mem_side_port(p.name + ".mem_side_port", *this, cpu_side_port, |
| ticksToCycles(p.delay), p.req_size), |
| num_lanes(p.num_lanes), |
| link_speed(p.link_speed) |
| { |
| } |
| |
| Port& |
| SerialLink::getPort(const std::string &if_name, PortID idx) |
| { |
| if (if_name == "mem_side_port") |
| return mem_side_port; |
| else if (if_name == "cpu_side_port") |
| return cpu_side_port; |
| else |
| // pass it along to our super class |
| return ClockedObject::getPort(if_name, idx); |
| } |
| |
| void |
| SerialLink::init() |
| { |
| // make sure both sides are connected and have the same block size |
| if (!cpu_side_port.isConnected() || !mem_side_port.isConnected()) |
| fatal("Both ports of a serial_link must be connected.\n"); |
| |
| // notify the request side of our address ranges |
| cpu_side_port.sendRangeChange(); |
| } |
| |
| bool |
| SerialLink::SerialLinkResponsePort::respQueueFull() const |
| { |
| return outstandingResponses == respQueueLimit; |
| } |
| |
| bool |
| SerialLink::SerialLinkRequestPort::reqQueueFull() const |
| { |
| return transmitList.size() == reqQueueLimit; |
| } |
| |
| bool |
| SerialLink::SerialLinkRequestPort::recvTimingResp(PacketPtr pkt) |
| { |
| // all checks are done when the request is accepted on the response |
| // side, so we are guaranteed to have space for the response |
| DPRINTF(SerialLink, "recvTimingResp: %s addr 0x%x\n", |
| pkt->cmdString(), pkt->getAddr()); |
| |
| DPRINTF(SerialLink, "Request queue size: %d\n", transmitList.size()); |
| |
| // @todo: We need to pay for this and not just zero it out |
| pkt->headerDelay = pkt->payloadDelay = 0; |
| |
| // This is similar to what happens for the request packets: |
| // The serializer will start serialization as soon as it receives the |
| // first flit, but the deserializer (at the host side in this case), will |
| // have to wait to receive the whole packet. So we only account for the |
| // deserialization latency. |
| Cycles cycles = delay; |
| cycles += Cycles(divCeil(pkt->getSize() * 8, serial_link.num_lanes |
| * serial_link.link_speed)); |
| Tick t = serial_link.clockEdge(cycles); |
| |
| //@todo: If the processor sends two uncached requests towards HMC and the |
| // second one is smaller than the first one. It may happen that the second |
| // one crosses this link faster than the first one (because the packet |
| // waits in the link based on its size). This can reorder the received |
| // response. |
| cpu_side_port.schedTimingResp(pkt, t); |
| |
| return true; |
| } |
| |
| bool |
| SerialLink::SerialLinkResponsePort::recvTimingReq(PacketPtr pkt) |
| { |
| DPRINTF(SerialLink, "recvTimingReq: %s addr 0x%x\n", |
| pkt->cmdString(), pkt->getAddr()); |
| |
| // we should not see a timing request if we are already in a retry |
| assert(!retryReq); |
| |
| DPRINTF(SerialLink, "Response queue size: %d outresp: %d\n", |
| transmitList.size(), outstandingResponses); |
| |
| // if the request queue is full then there is no hope |
| if (mem_side_port.reqQueueFull()) { |
| DPRINTF(SerialLink, "Request queue full\n"); |
| retryReq = true; |
| } else if ( !retryReq ) { |
| // look at the response queue if we expect to see a response |
| bool expects_response = pkt->needsResponse() && |
| !pkt->cacheResponding(); |
| if (expects_response) { |
| if (respQueueFull()) { |
| DPRINTF(SerialLink, "Response queue full\n"); |
| retryReq = true; |
| } else { |
| // ok to send the request with space for the response |
| DPRINTF(SerialLink, "Reserving space for response\n"); |
| assert(outstandingResponses != respQueueLimit); |
| ++outstandingResponses; |
| |
| // no need to set retryReq to false as this is already the |
| // case |
| } |
| } |
| |
| if (!retryReq) { |
| // @todo: We need to pay for this and not just zero it out |
| pkt->headerDelay = pkt->payloadDelay = 0; |
| |
| // We assume that the serializer component at the transmitter side |
| // does not need to receive the whole packet to start the |
| // serialization (this assumption is consistent with the HMC |
| // standard). But the deserializer waits for the complete packet |
| // to check its integrity first. So everytime a packet crosses a |
| // serial link, we should account for its deserialization latency |
| // only. |
| Cycles cycles = delay; |
| cycles += Cycles(divCeil(pkt->getSize() * 8, |
| serial_link.num_lanes * serial_link.link_speed)); |
| Tick t = serial_link.clockEdge(cycles); |
| |
| //@todo: If the processor sends two uncached requests towards HMC |
| // and the second one is smaller than the first one. It may happen |
| // that the second one crosses this link faster than the first one |
| // (because the packet waits in the link based on its size). |
| // This can reorder the received response. |
| mem_side_port.schedTimingReq(pkt, t); |
| } |
| } |
| |
| // remember that we are now stalling a packet and that we have to |
| // tell the sending requestor to retry once space becomes available, |
| // we make no distinction whether the stalling is due to the |
| // request queue or response queue being full |
| return !retryReq; |
| } |
| |
| void |
| SerialLink::SerialLinkResponsePort::retryStalledReq() |
| { |
| if (retryReq) { |
| DPRINTF(SerialLink, "Request waiting for retry, now retrying\n"); |
| retryReq = false; |
| sendRetryReq(); |
| } |
| } |
| |
| void |
| SerialLink::SerialLinkRequestPort::schedTimingReq(PacketPtr pkt, Tick when) |
| { |
| // If we're about to put this packet at the head of the queue, we |
| // need to schedule an event to do the transmit. Otherwise there |
| // should already be an event scheduled for sending the head |
| // packet. |
| if (transmitList.empty()) { |
| serial_link.schedule(sendEvent, when); |
| } |
| |
| assert(transmitList.size() != reqQueueLimit); |
| |
| transmitList.emplace_back(DeferredPacket(pkt, when)); |
| } |
| |
| |
| void |
| SerialLink::SerialLinkResponsePort::schedTimingResp(PacketPtr pkt, Tick when) |
| { |
| // If we're about to put this packet at the head of the queue, we |
| // need to schedule an event to do the transmit. Otherwise there |
| // should already be an event scheduled for sending the head |
| // packet. |
| if (transmitList.empty()) { |
| serial_link.schedule(sendEvent, when); |
| } |
| |
| transmitList.emplace_back(DeferredPacket(pkt, when)); |
| } |
| |
| void |
| SerialLink::SerialLinkRequestPort::trySendTiming() |
| { |
| assert(!transmitList.empty()); |
| |
| DeferredPacket req = transmitList.front(); |
| |
| assert(req.tick <= curTick()); |
| |
| PacketPtr pkt = req.pkt; |
| |
| DPRINTF(SerialLink, "trySend request addr 0x%x, queue size %d\n", |
| pkt->getAddr(), transmitList.size()); |
| |
| if (sendTimingReq(pkt)) { |
| // send successful |
| transmitList.pop_front(); |
| |
| DPRINTF(SerialLink, "trySend request successful\n"); |
| |
| // If there are more packets to send, schedule event to try again. |
| if (!transmitList.empty()) { |
| DeferredPacket next_req = transmitList.front(); |
| DPRINTF(SerialLink, "Scheduling next send\n"); |
| |
| // Make sure bandwidth limitation is met |
| Cycles cycles = Cycles(divCeil(pkt->getSize() * 8, |
| serial_link.num_lanes * serial_link.link_speed)); |
| Tick t = serial_link.clockEdge(cycles); |
| serial_link.schedule(sendEvent, std::max(next_req.tick, t)); |
| } |
| |
| // if we have stalled a request due to a full request queue, |
| // then send a retry at this point, also note that if the |
| // request we stalled was waiting for the response queue |
| // rather than the request queue we might stall it again |
| cpu_side_port.retryStalledReq(); |
| } |
| |
| // if the send failed, then we try again once we receive a retry, |
| // and therefore there is no need to take any action |
| } |
| |
| void |
| SerialLink::SerialLinkResponsePort::trySendTiming() |
| { |
| assert(!transmitList.empty()); |
| |
| DeferredPacket resp = transmitList.front(); |
| |
| assert(resp.tick <= curTick()); |
| |
| PacketPtr pkt = resp.pkt; |
| |
| DPRINTF(SerialLink, "trySend response addr 0x%x, outstanding %d\n", |
| pkt->getAddr(), outstandingResponses); |
| |
| if (sendTimingResp(pkt)) { |
| // send successful |
| transmitList.pop_front(); |
| DPRINTF(SerialLink, "trySend response successful\n"); |
| |
| assert(outstandingResponses != 0); |
| --outstandingResponses; |
| |
| // If there are more packets to send, schedule event to try again. |
| if (!transmitList.empty()) { |
| DeferredPacket next_resp = transmitList.front(); |
| DPRINTF(SerialLink, "Scheduling next send\n"); |
| |
| // Make sure bandwidth limitation is met |
| Cycles cycles = Cycles(divCeil(pkt->getSize() * 8, |
| serial_link.num_lanes * serial_link.link_speed)); |
| Tick t = serial_link.clockEdge(cycles); |
| serial_link.schedule(sendEvent, std::max(next_resp.tick, t)); |
| } |
| |
| // if there is space in the request queue and we were stalling |
| // a request, it will definitely be possible to accept it now |
| // since there is guaranteed space in the response queue |
| if (!mem_side_port.reqQueueFull() && retryReq) { |
| DPRINTF(SerialLink, "Request waiting for retry, now retrying\n"); |
| retryReq = false; |
| sendRetryReq(); |
| } |
| } |
| |
| // if the send failed, then we try again once we receive a retry, |
| // and therefore there is no need to take any action |
| } |
| |
| void |
| SerialLink::SerialLinkRequestPort::recvReqRetry() |
| { |
| trySendTiming(); |
| } |
| |
| void |
| SerialLink::SerialLinkResponsePort::recvRespRetry() |
| { |
| trySendTiming(); |
| } |
| |
| Tick |
| SerialLink::SerialLinkResponsePort::recvAtomic(PacketPtr pkt) |
| { |
| return delay * serial_link.clockPeriod() + mem_side_port.sendAtomic(pkt); |
| } |
| |
| void |
| SerialLink::SerialLinkResponsePort::recvFunctional(PacketPtr pkt) |
| { |
| pkt->pushLabel(name()); |
| |
| // check the response queue |
| for (auto i = transmitList.begin(); i != transmitList.end(); ++i) { |
| if (pkt->trySatisfyFunctional((*i).pkt)) { |
| pkt->makeResponse(); |
| return; |
| } |
| } |
| |
| // also check the memory-side port's request queue |
| if (mem_side_port.trySatisfyFunctional(pkt)) { |
| return; |
| } |
| |
| pkt->popLabel(); |
| |
| // fall through if pkt still not satisfied |
| mem_side_port.sendFunctional(pkt); |
| } |
| |
| bool |
| SerialLink::SerialLinkRequestPort::trySatisfyFunctional(PacketPtr pkt) |
| { |
| bool found = false; |
| auto i = transmitList.begin(); |
| |
| while (i != transmitList.end() && !found) { |
| if (pkt->trySatisfyFunctional((*i).pkt)) { |
| pkt->makeResponse(); |
| found = true; |
| } |
| ++i; |
| } |
| |
| return found; |
| } |
| |
| AddrRangeList |
| SerialLink::SerialLinkResponsePort::getAddrRanges() const |
| { |
| return ranges; |
| } |
| |
| } // namespace gem5 |
