src/sim/power/thermal_model.cc

   1 /*
   2  * Copyright (c) 2015 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
  38 #include "sim/power/thermal_model.hh"
  39
  40 #include "base/statistics.hh"
  41 #include "params/ThermalCapacitor.hh"
  42 #include "params/ThermalReference.hh"
  43 #include "params/ThermalResistor.hh"
  44 #include "sim/clocked_object.hh"
  45 #include "sim/linear_solver.hh"
  46 #include "sim/power/thermal_domain.hh"
  47 #include "sim/sim_object.hh"
  48
  49 /**
  50  * ThermalReference
  51  */
  52 ThermalReference::ThermalReference(const Params &p)
  53     : SimObject(p), _temperature(p.temperature), node(NULL)
  54 {
  55 }
  56
  57 void
  58 ThermalReference::serialize(CheckpointOut &cp) const
  59 {
  60     SERIALIZE_SCALAR(_temperature);
  61 }
  62
  63 void
  64 ThermalReference::unserialize(CheckpointIn &cp)
  65 {
  66     UNSERIALIZE_SCALAR(_temperature);
  67 }
  68
  69 LinearEquation
  70 ThermalReference::getEquation(ThermalNode * n, unsigned nnodes,
  71                               double step) const {
  72     // Just return an empty equation
  73     return LinearEquation(nnodes);
  74 }
  75
  76 /**
  77  * ThermalResistor
  78  */
  79 ThermalResistor::ThermalResistor(const Params &p)
  80     : SimObject(p), _resistance(p.resistance), node1(NULL), node2(NULL)
  81 {
  82 }
  83
  84 void
  85 ThermalResistor::serialize(CheckpointOut &cp) const
  86 {
  87     SERIALIZE_SCALAR(_resistance);
  88 }
  89
  90 void
  91 ThermalResistor::unserialize(CheckpointIn &cp)
  92 {
  93     UNSERIALIZE_SCALAR(_resistance);
  94 }
  95
  96 LinearEquation
  97 ThermalResistor::getEquation(ThermalNode * n, unsigned nnodes,
  98                              double step) const
  99 {
 100     // i[n] = (Vn2 - Vn1)/R
 101     LinearEquation eq(nnodes);
 102
 103     if (n != node1 && n != node2)
 104         return eq;
 105
 106     if (node1->isref)
 107         eq[eq.cnt()] += -node1->temp / _resistance;
 108     else
 109         eq[node1->id] += -1.0f / _resistance;
 110
 111     if (node2->isref)
 112         eq[eq.cnt()] += node2->temp / _resistance;
 113     else
 114         eq[node2->id] += 1.0f / _resistance;
 115
 116     // We've assumed n was node1, reverse if necessary
 117     if (n == node2)
 118         eq *= -1.0f;
 119
 120     return eq;
 121 }
 122
 123 /**
 124  * ThermalCapacitor
 125  */
 126 ThermalCapacitor::ThermalCapacitor(const Params &p)
 127     : SimObject(p), _capacitance(p.capacitance), node1(NULL), node2(NULL)
 128 {
 129 }
 130
 131 void
 132 ThermalCapacitor::serialize(CheckpointOut &cp) const
 133 {
 134     SERIALIZE_SCALAR(_capacitance);
 135 }
 136
 137 void
 138 ThermalCapacitor::unserialize(CheckpointIn &cp)
 139 {
 140     UNSERIALIZE_SCALAR(_capacitance);
 141 }
 142
 143 LinearEquation
 144 ThermalCapacitor::getEquation(ThermalNode * n, unsigned nnodes,
 145                               double step) const
 146 {
 147     // i(t) = C * d(Vn2 - Vn1)/dt
 148     // i[n] = C/step * (Vn2 - Vn1 - Vn2[n-1] + Vn1[n-1])
 149     LinearEquation eq(nnodes);
 150
 151     if (n != node1 && n != node2)
 152         return eq;
 153
 154     eq[eq.cnt()] += _capacitance / step * (node1->temp - node2->temp);
 155
 156     if (node1->isref)
 157         eq[eq.cnt()] += _capacitance / step * (-node1->temp);
 158     else
 159         eq[node1->id] += -1.0f * _capacitance / step;
 160
 161     if (node2->isref)
 162         eq[eq.cnt()] += _capacitance / step * (node2->temp);
 163     else
 164         eq[node2->id] += 1.0f * _capacitance / step;
 165
 166     // We've assumed n was node1, reverse if necessary
 167     if (n == node2)
 168         eq *= -1.0f;
 169
 170     return eq;
 171 }
 172
 173 /**
 174  * ThermalModel
 175  */
 176 ThermalModel::ThermalModel(const Params &p)
 177     : ClockedObject(p), stepEvent([this]{ doStep(); }, name()), _step(p.step)
 178 {
 179 }
 180
 181 void
 182 ThermalModel::serialize(CheckpointOut &cp) const
 183 {
 184     SERIALIZE_SCALAR(_step);
 185 }
 186
 187 void
 188 ThermalModel::unserialize(CheckpointIn &cp)
 189 {
 190     UNSERIALIZE_SCALAR(_step);
 191 }
 192
 193 void
 194 ThermalModel::doStep()
 195 {
 196     // Calculate new temperatures!
 197     // For each node in the system, create the kirchhoff nodal equation
 198     LinearSystem ls(eq_nodes.size());
 199     for (unsigned i = 0; i < eq_nodes.size(); i++) {
 200         auto n = eq_nodes[i];
 201         LinearEquation node_equation (eq_nodes.size());
 202         for (auto e : entities) {
 203             LinearEquation eq = e->getEquation(n, eq_nodes.size(), _step);
 204             node_equation = node_equation + eq;
 205         }
 206         ls[i] = node_equation;
 207     }
 208
 209     // Get temperatures for this iteration
 210     std::vector <double> temps = ls.solve();
 211     for (unsigned i = 0; i < eq_nodes.size(); i++)
 212         eq_nodes[i]->temp = temps[i];
 213
 214     // Schedule next computation
 215     schedule(stepEvent, curTick() + SimClock::Int::s * _step);
 216
 217     // Notify everybody
 218     for (auto dom : domains)
 219         dom->emitUpdate();
 220 }
 221
 222 void
 223 ThermalModel::startup()
 224 {
 225     // Look for nodes connected to voltage references, these
 226     // can be just set to the reference value (no nodal equation)
 227     for (auto ref : references) {
 228         ref->node->temp = ref->_temperature;
 229         ref->node->isref = true;
 230     }
 231     // Setup the initial temperatures
 232     for (auto dom : domains)
 233         dom->getNode()->temp = dom->initialTemperature();
 234
 235     // Create a list of unknown temperature nodes
 236     for (auto n : nodes) {
 237         bool found = false;
 238         for (auto ref : references)
 239             if (ref->node == n) {
 240                 found = true;
 241                 break;
 242             }
 243         if (!found)
 244             eq_nodes.push_back(n);
 245     }
 246
 247     // Assign each node an ID
 248     for (unsigned i = 0; i < eq_nodes.size(); i++)
 249         eq_nodes[i]->id = i;
 250
 251     // Schedule first thermal update
 252     schedule(stepEvent, curTick() + SimClock::Int::s * _step);
 253 }
 254
 255 void ThermalModel::addDomain(ThermalDomain * d) {
 256     domains.push_back(d);
 257     entities.push_back(d);
 258 }
 259 void ThermalModel::addReference(ThermalReference * r) {
 260     references.push_back(r);
 261     entities.push_back(r);
 262 }
 263 void ThermalModel::addCapacitor(ThermalCapacitor * c) {
 264     capacitors.push_back(c);
 265     entities.push_back(c);
 266 }
 267 void ThermalModel::addResistor(ThermalResistor * r) {
 268     resistors.push_back(r);
 269     entities.push_back(r);
 270 }
 271
 272 double ThermalModel::getTemp() const {
 273     // Just pick the highest temperature
 274     double temp = 0;
 275     for (auto & n : eq_nodes)
 276         temp = std::max(temp, n->temp);
 277     return temp;
 278 }