src/mem/qos/policy_pf.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
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   8  * to a hardware implementation of the functionality of the software
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  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
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  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
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  35  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  *
  37  * Author: Giacomo Travaglini
  38  */
  39
  40 #include "mem/qos/policy_pf.hh"
  41
  42 #include "mem/request.hh"
  43
  44 namespace QoS {
  45
  46 PropFairPolicy::PropFairPolicy(const Params* p)
  47   : Policy(p), weight(p->weight)
  48 {
  49     fatal_if(weight < 0 || weight > 1,
  50         "weight must be a value between 0 and 1");
  51 }
  52
  53 PropFairPolicy::~PropFairPolicy()
  54 {}
  55
  56 template <typename Requestor>
  57 void
  58 PropFairPolicy::initRequestor(const Requestor requestor, const double score)
  59 {
  60     RequestorID id = memCtrl->system()->lookupRequestorId(requestor);
  61
  62     assert(id != Request::invldRequestorId);
  63
  64     // Setting the Initial score for the selected requestor.
  65     history.push_back(std::make_pair(id, score));
  66
  67     fatal_if(history.size() > memCtrl->numPriorities(),
  68         "Policy's maximum number of requestors is currently dictated "
  69         "by the maximum number of priorities\n");
  70 }
  71
  72 void
  73 PropFairPolicy::initRequestorName(const std::string requestor, const double score)
  74 {
  75     initRequestor(requestor, score);
  76 }
  77
  78 void
  79 PropFairPolicy::initRequestorObj(const SimObject* requestor, const double score)
  80 {
  81     initRequestor(requestor, score);
  82 }
  83
  84 double
  85 PropFairPolicy::updateScore(
  86     const double old_score, const uint64_t served_bytes) const
  87 {
  88     return ((1.0 - weight) * old_score) + (weight * served_bytes);
  89 }
  90
  91 uint8_t
  92 PropFairPolicy::schedule(const RequestorID pkt_id, const uint64_t pkt_size)
  93 {
  94     auto sort_pred =
  95     [] (const RequestorHistory& lhs, const RequestorHistory& rhs)
  96     { return lhs.second > rhs.second; };
  97
  98     // Sorting in reverse in base of personal history:
  99     // First elements have higher history/score -> lower priority.
 100     // The qos priority is the position in the sorted vector.
 101     std::sort(history.begin(), history.end(), sort_pred);
 102
 103     const double served_bytes = static_cast<double>(pkt_size);
 104
 105     uint8_t pkt_priority = 0;
 106     for (auto m_hist = history.begin(); m_hist != history.end(); m_hist++) {
 107
 108         RequestorID curr_id = m_hist->first;
 109         double& curr_score = m_hist->second;
 110
 111         if (curr_id == pkt_id) {
 112             // The qos priority is the position in the sorted vector.
 113             pkt_priority = std::distance(history.begin(), m_hist);
 114
 115             curr_score = updateScore(curr_score, served_bytes);
 116         } else {
 117             curr_score = updateScore(curr_score, 0);
 118         }
 119     }
 120
 121     return pkt_priority;
 122 }
 123
 124 } // namespace QoS
 125
 126 QoS::PropFairPolicy *
 127 QoSPropFairPolicyParams::create()
 128 {
 129     return new QoS::PropFairPolicy(this);
 130 }