src/mem/ruby/network/garnet/NetworkBridge.cc

/*
 * Copyright (c) 2020 Advanced Micro Devices, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. Neither the name of the copyright holder 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 HOLDER 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
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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 */


#include "mem/ruby/network/garnet/NetworkBridge.hh"

#include <cmath>

#include "debug/RubyNetwork.hh"
#include "params/GarnetIntLink.hh"

namespace gem5
{

namespace ruby
{

namespace garnet
{

NetworkBridge::NetworkBridge(const Params &p)
    :CreditLink(p)
{
    enCdc = true;
    enSerDes = true;
    mType = p.vtype;

    cdcLatency = p.cdc_latency;
    serDesLatency = p.serdes_latency;
    lastScheduledAt = 0;

    nLink = p.link;
    if (mType == enums::LINK_OBJECT) {
        nLink->setLinkConsumer(this);
        setSourceQueue(nLink->getBuffer(), nLink);
    } else if (mType == enums::OBJECT_LINK) {
        nLink->setSourceQueue(&linkBuffer, this);
        setLinkConsumer(nLink);
    } else {
        // CDC type must be set
        panic("CDC type must be set");
    }
}

void
NetworkBridge::setVcsPerVnet(uint32_t consumerVcs)
{
    DPRINTF(RubyNetwork, "VcsPerVnet VC: %d\n", consumerVcs);
    NetworkLink::setVcsPerVnet(consumerVcs);
    lenBuffer.resize(consumerVcs * m_virt_nets);
    sizeSent.resize(consumerVcs * m_virt_nets);
    flitsSent.resize(consumerVcs * m_virt_nets);
    extraCredit.resize(consumerVcs * m_virt_nets);

    nLink->setVcsPerVnet(consumerVcs);
}

void
NetworkBridge::initBridge(NetworkBridge *coBrid, bool cdc_en, bool serdes_en)
{
    coBridge = coBrid;
    enCdc = cdc_en;
    enSerDes = serdes_en;
}

NetworkBridge::~NetworkBridge()
{
}

void
NetworkBridge::scheduleFlit(flit *t_flit, Cycles latency)
{
    Cycles totLatency = latency;

    if (enCdc) {
        // Add the CDC latency
        totLatency = latency + cdcLatency;
    }

    Tick sendTime = link_consumer->getObject()->clockEdge(totLatency);
    Tick nextAvailTick = lastScheduledAt + link_consumer->getObject()->\
            cyclesToTicks(Cycles(1));
    sendTime = std::max(nextAvailTick, sendTime);
    t_flit->set_time(sendTime);
    lastScheduledAt = sendTime;
    linkBuffer.insert(t_flit);
    link_consumer->scheduleEventAbsolute(sendTime);
}

void
NetworkBridge::neutralize(int vc, int eCredit)
{
    extraCredit[vc].push(eCredit);
}

void
NetworkBridge::flitisizeAndSend(flit *t_flit)
{
    // Serialize-Deserialize only if it is enabled
    if (enSerDes) {
        // Calculate the target-width
        int target_width = bitWidth;
        int cur_width = nLink->bitWidth;
        if (mType == enums::OBJECT_LINK) {
            target_width = nLink->bitWidth;
            cur_width = bitWidth;
        }

        DPRINTF(RubyNetwork, "Target width: %d Current: %d\n",
            target_width, cur_width);
        assert(target_width != cur_width);

        int vc = t_flit->get_vc();

        if (target_width > cur_width) {
            // Deserialize
            // This deserializer combines flits from the
            // same message together
            int num_flits = 0;
            int flitPossible = 0;
            if (t_flit->get_type() == CREDIT_) {
                lenBuffer[vc]++;
                assert(extraCredit[vc].front());
                if (lenBuffer[vc] == extraCredit[vc].front()) {
                    flitPossible = 1;
                    extraCredit[vc].pop();
                    lenBuffer[vc] = 0;
                }
            } else if (t_flit->get_type() == TAIL_ ||
                       t_flit->get_type() == HEAD_TAIL_) {
                // If its the end of packet, then send whatever
                // is available.
                int sizeAvail = (t_flit->msgSize - sizeSent[vc]);
                flitPossible = ceil((float)sizeAvail/(float)target_width);
                assert (flitPossible < 2);
                num_flits = (t_flit->get_id() + 1) - flitsSent[vc];
                // Stop tracking the packet.
                flitsSent[vc] = 0;
                sizeSent[vc] = 0;
            } else {
                // If we are yet to receive the complete packet
                // track the size recieved and flits deserialized.
                int sizeAvail =
                    ((t_flit->get_id() + 1)*cur_width) - sizeSent[vc];
                flitPossible = floor((float)sizeAvail/(float)target_width);
                assert (flitPossible < 2);
                num_flits = (t_flit->get_id() + 1) - flitsSent[vc];
                if (flitPossible) {
                    sizeSent[vc] += target_width;
                    flitsSent[vc] = t_flit->get_id() + 1;
                }
            }

            DPRINTF(RubyNetwork, "Deserialize :%dB -----> %dB "
                " vc:%d\n", cur_width, target_width, vc);

            flit *fl = NULL;
            if (flitPossible) {
                fl = t_flit->deserialize(lenBuffer[vc], num_flits,
                    target_width);
            }

            // Inform the credit serializer about the number
            // of flits that were generated.
            if (t_flit->get_type() != CREDIT_ && fl) {
                coBridge->neutralize(vc, num_flits);
            }

            // Schedule only if we are done deserializing
            if (fl) {
                DPRINTF(RubyNetwork, "Scheduling a flit\n");
                lenBuffer[vc] = 0;
                scheduleFlit(fl, serDesLatency);
            }
            // Delete this flit, new flit is sent in any case
            delete t_flit;
        } else {
            // Serialize
            DPRINTF(RubyNetwork, "Serializing flit :%d -----> %d "
            "(vc:%d, Original Message Size: %d)\n",
                cur_width, target_width, vc, t_flit->msgSize);

            int flitPossible = 0;
            if (t_flit->get_type() == CREDIT_) {
                // We store the deserialization ratio and then
                // access it when serializing credits in the
                // oppposite direction.
                assert(extraCredit[vc].front());
                flitPossible = extraCredit[vc].front();
                extraCredit[vc].pop();
            } else if (t_flit->get_type() == HEAD_ ||
                    t_flit->get_type() == BODY_) {
                int sizeAvail =
                    ((t_flit->get_id() + 1)*cur_width) - sizeSent[vc];
                flitPossible = floor((float)sizeAvail/(float)target_width);
                if (flitPossible) {
                    sizeSent[vc] += flitPossible*target_width;
                    flitsSent[vc] += flitPossible;
                }
            } else {
                int sizeAvail = t_flit->msgSize - sizeSent[vc];
                flitPossible = ceil((float)sizeAvail/(float)target_width);
                sizeSent[vc] = 0;
                flitsSent[vc] = 0;
            }
            assert(flitPossible > 0);

            // Schedule all the flits
            // num_flits could be zero for credits
            for (int i = 0; i < flitPossible; i++) {
                // Ignore neutralized credits
                flit *fl = t_flit->serialize(i, flitPossible, target_width);
                scheduleFlit(fl, serDesLatency);
                DPRINTF(RubyNetwork, "Serialized to flit[%d of %d parts]:"
                " %s\n", i+1, flitPossible, *fl);
            }

            if (t_flit->get_type() != CREDIT_) {
                coBridge->neutralize(vc, flitPossible);
            }
            // Delete this flit, new flit is sent in any case
            delete t_flit;
        }
        return;
    }

    // If only CDC is enabled schedule it
    scheduleFlit(t_flit, Cycles(0));
}
void
NetworkBridge::wakeup()
{
    flit *t_flit;

    if (link_srcQueue->isReady(curTick())) {
        t_flit = link_srcQueue->getTopFlit();
        DPRINTF(RubyNetwork, "Recieved flit %s\n", *t_flit);
        flitisizeAndSend(t_flit);
    }

    // Reschedule in case there is a waiting flit.
    if (!link_srcQueue->isEmpty()) {
        scheduleEvent(Cycles(1));
    }
}

} // namespace garnet
} // namespace ruby
} // namespace gem5