src/mem/qos/q_policy.cc

   1 /*
   2  * Copyright (c) 2018 ARM Limited
   3  * All rights reserved
   4  *
   5  * The license below extends only to copyright in the software and shall
   6  * not be construed as granting a license to any other intellectual
   7  * property including but not limited to intellectual property relating
   8  * to a hardware implementation of the functionality of the software
   9  * licensed hereunder.  You may use the software subject to the license
  10  * terms below provided that you ensure that this notice is replicated
  11  * unmodified and in its entirety in all distributions of the software,
  12  * modified or unmodified, in source code or in binary form.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions are
  16  * met: redistributions of source code must retain the above copyright
  17  * notice, this list of conditions and the following disclaimer;
  18  * redistributions in binary form must reproduce the above copyright
  19  * notice, this list of conditions and the following disclaimer in the
  20  * documentation and/or other materials provided with the distribution;
  21  * neither the name of the copyright holders nor the names of its
  22  * contributors may be used to endorse or promote products derived from
  23  * this software without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  26  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  27  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  28  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  29  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  31  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  35  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  *
  37  * Author: Matteo Andreozzi
  38  */
  39
  40 #include "mem/qos/q_policy.hh"
  41
  42 #include <unordered_map>
  43 #include <utility>
  44
  45 #include "debug/QOS.hh"
  46 #include "enums/QoSQPolicy.hh"
  47 #include "mem/qos/mem_ctrl.hh"
  48
  49 namespace QoS {
  50
  51 QueuePolicy*
  52 QueuePolicy::create(const QoSMemCtrlParams* p)
  53 {
  54     switch (p->qos_q_policy) {
  55       case Enums::QoSQPolicy::fifo:
  56         return new FifoQueuePolicy(p);
  57       case Enums::QoSQPolicy::lrg:
  58         return new LrgQueuePolicy(p);
  59       case Enums::QoSQPolicy::lifo:
  60       default:
  61         return new LifoQueuePolicy(p);
  62     }
  63 }
  64
  65 QueuePolicy::PacketQueue::iterator
  66 LrgQueuePolicy::selectPacket(PacketQueue* q)
  67 {
  68     QueuePolicy::PacketQueue::iterator ret = q->end();
  69
  70     // Tracks one packet per master in the queue
  71     std::unordered_map<MasterID, QueuePolicy::PacketQueue::iterator> track;
  72
  73     // Cycle queue only once
  74     for (auto pkt_it = q->begin(); pkt_it != q->end(); ++pkt_it) {
  75
  76         const auto& pkt = *pkt_it;
  77
  78         panic_if(!pkt->req,
  79                  "QoSQPolicy::lrg detected packet without request");
  80
  81         // Get Request MasterID
  82         MasterID m_id = pkt->req->masterId();
  83         DPRINTF(QOS, "QoSQPolicy::lrg checking packet "
  84                      "from queue with id %d\n", m_id);
  85
  86         // Check if this is a known master.
  87         panic_if(memCtrl->hasMaster(m_id),
  88                  "%s: Unrecognized Master\n", __func__);
  89
  90         panic_if(toServe.size() > 0,
  91                  "%s: toServe list is empty\n", __func__);
  92
  93         if (toServe.front() == m_id) {
  94             DPRINTF(QOS, "QoSQPolicy::lrg matched to served "
  95                          "master id %d\n", m_id);
  96             // This packet matches the MasterID to be served next
  97             // move toServe front to back
  98             toServe.push_back(m_id);
  99             toServe.pop_front();
 100
 101             return pkt_it;
 102         }
 103
 104         // The master generating the packet is not first in the toServe list
 105         // (Doesn't have the highest priority among masters)
 106         // Check if this is the first packet seen with its master ID
 107         // and remember it. Then keep looping over the remaining packets
 108         // in the queue.
 109         if (track.find(m_id) == track.end()) {
 110             track[m_id] = pkt_it;
 111             DPRINTF(QOS, "QoSQPolicy::lrg tracking a packet for "
 112                          "master id %d\n", m_id);
 113         }
 114     }
 115
 116     // If here, the current master to be serviced doesn't have a pending
 117     // packet in the queue: look for the next master in the list.
 118     for (const auto& masterId : toServe) {
 119         DPRINTF(QOS, "QoSQPolicy::lrg evaluating alternative "
 120                      "master id %d\n", masterId);
 121
 122         if (track.find(masterId) != track.end()) {
 123             ret = track[masterId];
 124             DPRINTF(QOS, "QoSQPolicy::lrg master id "
 125                          "%d selected for service\n", masterId);
 126
 127             return ret;
 128         }
 129     }
 130
 131     DPRINTF(QOS, "QoSQPolicy::lrg no packet was serviced\n");
 132
 133     // Ret will be : packet to serve if any found or queue begin
 134     // (end if queue is empty)
 135     return ret;
 136 }
 137
 138 void
 139 LrgQueuePolicy::enqueuePacket(PacketPtr pkt)
 140 {
 141     MasterID m_id = pkt->masterId();
 142     if (!memCtrl->hasMaster(m_id)) {
 143         toServe.push_back(m_id);
 144     }
 145 };
 146
 147 } // namespace QoS