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;
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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
  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  * Authors: David Guillen Fandos
  38  */
  39
  40 #include "sim/power/thermal_model.hh"
  41
  42 #include "base/statistics.hh"
  43 #include "params/ThermalCapacitor.hh"
  44 #include "params/ThermalReference.hh"
  45 #include "params/ThermalResistor.hh"
  46 #include "sim/clocked_object.hh"
  47 #include "sim/linear_solver.hh"
  48 #include "sim/power/thermal_domain.hh"
  49 #include "sim/sim_object.hh"
  50
  51 /**
  52  * ThermalReference
  53  */
  54 ThermalReference::ThermalReference(const Params *p)
  55     : SimObject(p), _temperature(p->temperature), node(NULL)
  56 {
  57 }
  58
  59 ThermalReference *
  60 ThermalReferenceParams::create()
  61 {
  62     return new ThermalReference(this);
  63 }
  64
  65 void
  66 ThermalReference::serialize(CheckpointOut &cp) const
  67 {
  68     SERIALIZE_SCALAR(_temperature);
  69 }
  70
  71 void
  72 ThermalReference::unserialize(CheckpointIn &cp)
  73 {
  74     UNSERIALIZE_SCALAR(_temperature);
  75 }
  76
  77 LinearEquation
  78 ThermalReference::getEquation(ThermalNode * n, unsigned nnodes,
  79                               double step) const {
  80     // Just return an empty equation
  81     return LinearEquation(nnodes);
  82 }
  83
  84 /**
  85  * ThermalResistor
  86  */
  87 ThermalResistor::ThermalResistor(const Params *p)
  88     : SimObject(p), _resistance(p->resistance), node1(NULL), node2(NULL)
  89 {
  90 }
  91
  92 ThermalResistor *
  93 ThermalResistorParams::create()
  94 {
  95     return new ThermalResistor(this);
  96 }
  97
  98 void
  99 ThermalResistor::serialize(CheckpointOut &cp) const
 100 {
 101     SERIALIZE_SCALAR(_resistance);
 102 }
 103
 104 void
 105 ThermalResistor::unserialize(CheckpointIn &cp)
 106 {
 107     UNSERIALIZE_SCALAR(_resistance);
 108 }
 109
 110 LinearEquation
 111 ThermalResistor::getEquation(ThermalNode * n, unsigned nnodes,
 112                              double step) const
 113 {
 114     // i[n] = (Vn2 - Vn1)/R
 115     LinearEquation eq(nnodes);
 116
 117     if (n != node1 && n != node2)
 118         return eq;
 119
 120     if (node1->isref)
 121         eq[eq.cnt()] += -node1->temp / _resistance;
 122     else
 123         eq[node1->id] += -1.0f / _resistance;
 124
 125     if (node2->isref)
 126         eq[eq.cnt()] += node2->temp / _resistance;
 127     else
 128         eq[node2->id] += 1.0f / _resistance;
 129
 130     // We've assumed n was node1, reverse if necessary
 131     if (n == node2)
 132         eq *= -1.0f;
 133
 134     return eq;
 135 }
 136
 137 /**
 138  * ThermalCapacitor
 139  */
 140 ThermalCapacitor::ThermalCapacitor(const Params *p)
 141     : SimObject(p), _capacitance(p->capacitance), node1(NULL), node2(NULL)
 142 {
 143 }
 144
 145 ThermalCapacitor *
 146 ThermalCapacitorParams::create()
 147 {
 148     return new ThermalCapacitor(this);
 149 }
 150
 151 void
 152 ThermalCapacitor::serialize(CheckpointOut &cp) const
 153 {
 154     SERIALIZE_SCALAR(_capacitance);
 155 }
 156
 157 void
 158 ThermalCapacitor::unserialize(CheckpointIn &cp)
 159 {
 160     UNSERIALIZE_SCALAR(_capacitance);
 161 }
 162
 163 LinearEquation
 164 ThermalCapacitor::getEquation(ThermalNode * n, unsigned nnodes,
 165                               double step) const
 166 {
 167     // i(t) = C * d(Vn2 - Vn1)/dt
 168     // i[n] = C/step * (Vn2 - Vn1 - Vn2[n-1] + Vn1[n-1])
 169     LinearEquation eq(nnodes);
 170
 171     if (n != node1 && n != node2)
 172         return eq;
 173
 174     eq[eq.cnt()] += _capacitance / step * (node1->temp - node2->temp);
 175
 176     if (node1->isref)
 177         eq[eq.cnt()] += _capacitance / step * (-node1->temp);
 178     else
 179         eq[node1->id] += -1.0f * _capacitance / step;
 180
 181     if (node2->isref)
 182         eq[eq.cnt()] += _capacitance / step * (node2->temp);
 183     else
 184         eq[node2->id] += 1.0f * _capacitance / step;
 185
 186     // We've assumed n was node1, reverse if necessary
 187     if (n == node2)
 188         eq *= -1.0f;
 189
 190     return eq;
 191 }
 192
 193 /**
 194  * ThermalModel
 195  */
 196 ThermalModel::ThermalModel(const Params *p)
 197     : ClockedObject(p), stepEvent([this]{ doStep(); }, name()), _step(p->step)
 198 {
 199 }
 200
 201 ThermalModel *
 202 ThermalModelParams::create()
 203 {
 204     return new ThermalModel(this);
 205 }
 206
 207 void
 208 ThermalModel::serialize(CheckpointOut &cp) const
 209 {
 210     SERIALIZE_SCALAR(_step);
 211 }
 212
 213 void
 214 ThermalModel::unserialize(CheckpointIn &cp)
 215 {
 216     UNSERIALIZE_SCALAR(_step);
 217 }
 218
 219 void
 220 ThermalModel::doStep()
 221 {
 222     // Calculate new temperatures!
 223     // For each node in the system, create the kirchhoff nodal equation
 224     LinearSystem ls(eq_nodes.size());
 225     for (unsigned i = 0; i < eq_nodes.size(); i++) {
 226         auto n = eq_nodes[i];
 227         LinearEquation node_equation (eq_nodes.size());
 228         for (auto e : entities) {
 229             LinearEquation eq = e->getEquation(n, eq_nodes.size(), _step);
 230             node_equation = node_equation + eq;
 231         }
 232         ls[i] = node_equation;
 233     }
 234
 235     // Get temperatures for this iteration
 236     std::vector <double> temps = ls.solve();
 237     for (unsigned i = 0; i < eq_nodes.size(); i++)
 238         eq_nodes[i]->temp = temps[i];
 239
 240     // Schedule next computation
 241     schedule(stepEvent, curTick() + SimClock::Int::s * _step);
 242
 243     // Notify everybody
 244     for (auto dom : domains)
 245         dom->emitUpdate();
 246 }
 247
 248 void
 249 ThermalModel::startup()
 250 {
 251     // Look for nodes connected to voltage references, these
 252     // can be just set to the reference value (no nodal equation)
 253     for (auto ref : references) {
 254         ref->node->temp = ref->_temperature;
 255         ref->node->isref = true;
 256     }
 257     // Setup the initial temperatures
 258     for (auto dom : domains)
 259         dom->getNode()->temp = dom->initialTemperature();
 260
 261     // Create a list of unknown temperature nodes
 262     for (auto n : nodes) {
 263         bool found = false;
 264         for (auto ref : references)
 265             if (ref->node == n) {
 266                 found = true;
 267                 break;
 268             }
 269         if (!found)
 270             eq_nodes.push_back(n);
 271     }
 272
 273     // Assign each node an ID
 274     for (unsigned i = 0; i < eq_nodes.size(); i++)
 275         eq_nodes[i]->id = i;
 276
 277     // Schedule first thermal update
 278     schedule(stepEvent, curTick() + SimClock::Int::s * _step);
 279 }
 280
 281 void ThermalModel::addDomain(ThermalDomain * d) {
 282     domains.push_back(d);
 283     entities.push_back(d);
 284 }
 285 void ThermalModel::addReference(ThermalReference * r) {
 286     references.push_back(r);
 287     entities.push_back(r);
 288 }
 289 void ThermalModel::addCapacitor(ThermalCapacitor * c) {
 290     capacitors.push_back(c);
 291     entities.push_back(c);
 292 }
 293 void ThermalModel::addResistor(ThermalResistor * r) {
 294     resistors.push_back(r);
 295     entities.push_back(r);
 296 }
 297
 298 double ThermalModel::getTemp() const {
 299     // Just pick the highest temperature
 300     double temp = 0;
 301     for (auto & n : eq_nodes)
 302         temp = std::max(temp, n->temp);
 303     return temp;
 304 }