PerfectSwitch.cc

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/*
 * Copyright (c) 1999-2008 Mark D. Hill and David A. Wood
 * 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
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#include "mem/ruby/network/simple/PerfectSwitch.hh"
 
#include <algorithm>
 
#include "base/cast.hh"
#include "base/cprintf.hh"
#include "base/random.hh"
#include "debug/RubyNetwork.hh"
#include "mem/ruby/network/MessageBuffer.hh"
#include "mem/ruby/network/simple/SimpleNetwork.hh"
#include "mem/ruby/network/simple/Switch.hh"
#include "mem/ruby/slicc_interface/Message.hh"
 
namespace gem5
{
 
namespace ruby
{
 
const int PRIORITY_SWITCH_LIMIT = 128;
 
// Operator for helper class
bool
operator<(const LinkOrder& l1, const LinkOrder& l2)
{
    return (l1.m_value < l2.m_value);
}
 
PerfectSwitch::PerfectSwitch(SwitchID sid, Switch *sw, uint32_t virt_nets)
    : Consumer(sw), m_switch_id(sid), m_switch(sw)
{
    m_round_robin_start = 0;
    m_wakeups_wo_switch = 0;
    m_virtual_networks = virt_nets;
}
 
void
PerfectSwitch::init(SimpleNetwork *network_ptr)
{
    m_network_ptr = network_ptr;
 
    for (int i = 0;i < m_virtual_networks;++i) {
        m_pending_message_count.push_back(0);
    }
}
 
void
PerfectSwitch::addInPort(const std::vector<MessageBuffer*>& in)
{
    NodeID port = m_in.size();
    m_in.push_back(in);
 
    for (int i = 0; i < in.size(); ++i) {
        if (in[i] != nullptr) {
            in[i]->setConsumer(this);
            in[i]->setIncomingLink(port);
            in[i]->setVnet(i);
        }
    }
}
 
void
PerfectSwitch::addOutPort(const std::vector<MessageBuffer*>& out,
                          const NetDest& routing_table_entry)
{
    // Setup link order
    LinkOrder l;
    l.m_value = 0;
    l.m_link = m_out.size();
    m_link_order.push_back(l);
 
    // Add to routing table
    m_out.push_back(out);
    m_routing_table.push_back(routing_table_entry);
}
 
PerfectSwitch::~PerfectSwitch()
{
}
 
void
PerfectSwitch::operateVnet(int vnet)
{
    // This is for round-robin scheduling
    int incoming = m_round_robin_start;
    m_round_robin_start++;
    if (m_round_robin_start >= m_in.size()) {
        m_round_robin_start = 0;
    }
 
    if (m_pending_message_count[vnet] > 0) {
        // for all input ports, use round robin scheduling
        for (int counter = 0; counter < m_in.size(); counter++) {
            // Round robin scheduling
            incoming++;
            if (incoming >= m_in.size()) {
                incoming = 0;
            }
 
            // Is there a message waiting?
            if (m_in[incoming].size() <= vnet) {
                continue;
            }
 
            MessageBuffer *buffer = m_in[incoming][vnet];
            if (buffer == nullptr) {
                continue;
            }
 
            operateMessageBuffer(buffer, incoming, vnet);
        }
    }
}
 
void
PerfectSwitch::operateMessageBuffer(MessageBuffer *buffer, int incoming,
                                    int vnet)
{
    MsgPtr msg_ptr;
    Message *net_msg_ptr = NULL;
 
    // temporary vectors to store the routing results
    std::vector<LinkID> output_links;
    std::vector<NetDest> output_link_destinations;
    Tick current_time = m_switch->clockEdge();
 
    while (buffer->isReady(current_time)) {
        DPRINTF(RubyNetwork, "incoming: %d\n", incoming);
 
        // Peek at message
        msg_ptr = buffer->peekMsgPtr();
        net_msg_ptr = msg_ptr.get();
        DPRINTF(RubyNetwork, "Message: %s\n", (*net_msg_ptr));
 
        output_links.clear();
        output_link_destinations.clear();
        NetDest msg_dsts = net_msg_ptr->getDestination();
 
        // Unfortunately, the token-protocol sends some
        // zero-destination messages, so this assert isn't valid
        // assert(msg_dsts.count() > 0);
 
        assert(m_link_order.size() == m_routing_table.size());
        assert(m_link_order.size() == m_out.size());
 
        if (m_network_ptr->getAdaptiveRouting()) {
            if (m_network_ptr->isVNetOrdered(vnet)) {
                // Don't adaptively route
                for (int out = 0; out < m_out.size(); out++) {
                    m_link_order[out].m_link = out;
                    m_link_order[out].m_value = 0;
                }
            } else {
                // Find how clogged each link is
                for (int out = 0; out < m_out.size(); out++) {
                    int out_queue_length = 0;
                    for (int v = 0; v < m_virtual_networks; v++) {
                        out_queue_length += m_out[out][v]->getSize(current_time);
                    }
                    int value =
                        (out_queue_length << 8) |
                        random_mt.random(0, 0xff);
                    m_link_order[out].m_link = out;
                    m_link_order[out].m_value = value;
                }
 
                // Look at the most empty link first
                sort(m_link_order.begin(), m_link_order.end());
            }
        }
 
        for (int i = 0; i < m_routing_table.size(); i++) {
            // pick the next link to look at
            int link = m_link_order[i].m_link;
            NetDest dst = m_routing_table[link];
            DPRINTF(RubyNetwork, "dst: %s\n", dst);
 
            if (!msg_dsts.intersectionIsNotEmpty(dst))
                continue;
 
            // Remember what link we're using
            output_links.push_back(link);
 
            // Need to remember which destinations need this message in
            // another vector.  This Set is the intersection of the
            // routing_table entry and the current destination set.  The
            // intersection must not be empty, since we are inside "if"
            output_link_destinations.push_back(msg_dsts.AND(dst));
 
            // Next, we update the msg_destination not to include
            // those nodes that were already handled by this link
            msg_dsts.removeNetDest(dst);
        }
 
        assert(msg_dsts.count() == 0);
 
        // Check for resources - for all outgoing queues
        bool enough = true;
        for (int i = 0; i < output_links.size(); i++) {
            int outgoing = output_links[i];
 
            if (!m_out[outgoing][vnet]->areNSlotsAvailable(1, current_time))
                enough = false;
 
            DPRINTF(RubyNetwork, "Checking if node is blocked ..."
                    "outgoing: %d, vnet: %d, enough: %d\n",
                    outgoing, vnet, enough);
        }
 
        // There were not enough resources
        if (!enough) {
            scheduleEvent(Cycles(1));
            DPRINTF(RubyNetwork, "Can't deliver message since a node "
                    "is blocked\n");
            DPRINTF(RubyNetwork, "Message: %s\n", (*net_msg_ptr));
            break; // go to next incoming port
        }
 
        MsgPtr unmodified_msg_ptr;
 
        if (output_links.size() > 1) {
            // If we are sending this message down more than one link
            // (size>1), we need to make a copy of the message so each
            // branch can have a different internal destination we need
            // to create an unmodified MsgPtr because the MessageBuffer
            // enqueue func will modify the message
 
            // This magic line creates a private copy of the message
            unmodified_msg_ptr = msg_ptr->clone();
        }
 
        // Dequeue msg
        buffer->dequeue(current_time);
        m_pending_message_count[vnet]--;
 
        // Enqueue it - for all outgoing queues
        for (int i=0; i<output_links.size(); i++) {
            int outgoing = output_links[i];
 
            if (i > 0) {
                // create a private copy of the unmodified message
                msg_ptr = unmodified_msg_ptr->clone();
            }
 
            // Change the internal destination set of the message so it
            // knows which destinations this link is responsible for.
            net_msg_ptr = msg_ptr.get();
            net_msg_ptr->getDestination() = output_link_destinations[i];
 
            // Enqeue msg
            DPRINTF(RubyNetwork, "Enqueuing net msg from "
                    "inport[%d][%d] to outport [%d][%d].\n",
                    incoming, vnet, outgoing, vnet);
 
            m_out[outgoing][vnet]->enqueue(msg_ptr, current_time,
                                           m_switch->cyclesToTicks(Cycles(1)));
        }
    }
}
 
void
PerfectSwitch::wakeup()
{
    // Give the highest numbered link priority most of the time
    m_wakeups_wo_switch++;
    int highest_prio_vnet = m_virtual_networks-1;
    int lowest_prio_vnet = 0;
    int decrementer = 1;
 
    // invert priorities to avoid starvation seen in the component network
    if (m_wakeups_wo_switch > PRIORITY_SWITCH_LIMIT) {
        m_wakeups_wo_switch = 0;
        highest_prio_vnet = 0;
        lowest_prio_vnet = m_virtual_networks-1;
        decrementer = -1;
    }
 
    // For all components incoming queues
    for (int vnet = highest_prio_vnet;
         (vnet * decrementer) >= (decrementer * lowest_prio_vnet);
         vnet -= decrementer) {
        operateVnet(vnet);
    }
}
 
void
PerfectSwitch::storeEventInfo(int info)
{
    m_pending_message_count[info]++;
}
 
void
PerfectSwitch::clearStats()
{
}
void
PerfectSwitch::collateStats()
{
}
 
 
void
PerfectSwitch::print(std::ostream& out) const
{
    out << "[PerfectSwitch " << m_switch_id << "]";
}
 
} // namespace ruby
} // namespace gem5