gem5  v21.1.0.2
thermal_model.cc
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37 
39 
40 #include "base/statistics.hh"
41 #include "params/ThermalCapacitor.hh"
42 #include "params/ThermalModel.hh"
43 #include "params/ThermalReference.hh"
44 #include "params/ThermalResistor.hh"
45 #include "sim/clocked_object.hh"
46 #include "sim/linear_solver.hh"
48 #include "sim/sim_object.hh"
49 
50 namespace gem5
51 {
52 
57  : SimObject(p), _temperature(p.temperature), node(NULL)
58 {
59 }
60 
63  double step) const {
64  // Just return an empty equation
65  return LinearEquation(nnodes);
66 }
67 
72  : SimObject(p), _resistance(p.resistance), node1(NULL), node2(NULL)
73 {
74 }
75 
78  double step) const
79 {
80  // i[n] = (Vn2 - Vn1)/R
81  LinearEquation eq(nnodes);
82 
83  if (n != node1 && n != node2)
84  return eq;
85 
86  if (node1->isref)
87  eq[eq.cnt()] += -node1->temp.toKelvin() / _resistance;
88  else
89  eq[node1->id] += -1.0f / _resistance;
90 
91  if (node2->isref)
92  eq[eq.cnt()] += node2->temp.toKelvin() / _resistance;
93  else
94  eq[node2->id] += 1.0f / _resistance;
95 
96  // We've assumed n was node1, reverse if necessary
97  if (n == node2)
98  eq *= -1.0f;
99 
100  return eq;
101 }
102 
107  : SimObject(p), _capacitance(p.capacitance), node1(NULL), node2(NULL)
108 {
109 }
110 
113  double step) const
114 {
115  // i(t) = C * d(Vn2 - Vn1)/dt
116  // i[n] = C/step * (Vn2 - Vn1 - Vn2[n-1] + Vn1[n-1])
117  LinearEquation eq(nnodes);
118 
119  if (n != node1 && n != node2)
120  return eq;
121 
122  eq[eq.cnt()] += _capacitance / step *
123  (node1->temp - node2->temp).toKelvin();
124 
125  if (node1->isref)
126  eq[eq.cnt()] += _capacitance / step * (-node1->temp.toKelvin());
127  else
128  eq[node1->id] += -1.0f * _capacitance / step;
129 
130  if (node2->isref)
131  eq[eq.cnt()] += _capacitance / step * (node2->temp.toKelvin());
132  else
133  eq[node2->id] += 1.0f * _capacitance / step;
134 
135  // We've assumed n was node1, reverse if necessary
136  if (n == node2)
137  eq *= -1.0f;
138 
139  return eq;
140 }
141 
146  : ClockedObject(p), stepEvent([this]{ doStep(); }, name()), _step(p.step)
147 {
148 }
149 
150 void
152 {
153  // Calculate new temperatures!
154  // For each node in the system, create the kirchhoff nodal equation
155  LinearSystem ls(eq_nodes.size());
156  for (unsigned i = 0; i < eq_nodes.size(); i++) {
157  auto n = eq_nodes[i];
158  LinearEquation node_equation (eq_nodes.size());
159  for (auto e : entities) {
160  LinearEquation eq = e->getEquation(n, eq_nodes.size(), _step);
161  node_equation = node_equation + eq;
162  }
163  ls[i] = node_equation;
164  }
165 
166  // Get temperatures for this iteration
167  std::vector <double> temps = ls.solve();
168  for (unsigned i = 0; i < eq_nodes.size(); i++)
169  eq_nodes[i]->temp = Temperature::fromKelvin(temps[i]);
170 
171  // Schedule next computation
173 
174  // Notify everybody
175  for (auto dom : domains)
176  dom->emitUpdate();
177 }
178 
179 void
181 {
182  // Look for nodes connected to voltage references, these
183  // can be just set to the reference value (no nodal equation)
184  for (auto ref : references) {
185  ref->node->temp = ref->_temperature;
186  ref->node->isref = true;
187  }
188  // Setup the initial temperatures
189  for (auto dom : domains)
190  dom->getNode()->temp = dom->initialTemperature();
191 
192  // Create a list of unknown temperature nodes
193  for (auto n : nodes) {
194  bool found = false;
195  for (auto ref : references)
196  if (ref->node == n) {
197  found = true;
198  break;
199  }
200  if (!found)
201  eq_nodes.push_back(n);
202  }
203 
204  // Assign each node an ID
205  for (unsigned i = 0; i < eq_nodes.size(); i++)
206  eq_nodes[i]->id = i;
207 
208  // Schedule first thermal update
210 }
211 
212 void
214 {
215  domains.push_back(d);
216  entities.push_back(d);
217 }
218 
219 void
221 {
222  references.push_back(r);
223  entities.push_back(r);
224 }
225 
226 void
228 {
229  capacitors.push_back(c);
230  entities.push_back(c);
231 }
232 
233 void
235 {
236  resistors.push_back(r);
237  entities.push_back(r);
238 }
239 
242 {
243  // Just pick the highest temperature
245  for (auto & n : eq_nodes)
246  temp = std::max(temp, n->temp);
247  return temp;
248 }
249 
250 } // namespace gem5
gem5::ThermalModel::eq_nodes
std::vector< ThermalNode * > eq_nodes
Definition: thermal_model.hh:174
gem5::curTick
Tick curTick()
The universal simulation clock.
Definition: cur_tick.hh:46
gem5::LinearSystem::solve
std::vector< double > solve() const
Definition: linear_solver.cc:44
gem5::ThermalResistor::getEquation
LinearEquation getEquation(ThermalNode *tn, unsigned n, double step) const override
Definition: thermal_model.cc:77
gem5::ThermalReference::getEquation
LinearEquation getEquation(ThermalNode *tn, unsigned n, double step) const override
Definition: thermal_model.cc:62
gem5::ThermalModel::addReference
void addReference(ThermalReference *r)
Definition: thermal_model.cc:220
gem5::ThermalModel::domains
std::vector< ThermalDomain * > domains
Definition: thermal_model.hh:165
gem5::ArmISA::e
Bitfield< 9 > e
Definition: misc_types.hh:64
gem5::ThermalModel::addCapacitor
void addCapacitor(ThermalCapacitor *c)
Definition: thermal_model.cc:227
gem5::EventManager::schedule
void schedule(Event &event, Tick when)
Definition: eventq.hh:1019
std::vector< double >
thermal_model.hh
gem5::sim_clock::as_int::s
Tick s
second
Definition: core.cc:68
gem5::Temperature
The class stores temperatures in Kelvin and provides helper methods to convert to/from Celsius.
Definition: temperature.hh:50
gem5::ThermalCapacitor::_capacitance
const double _capacitance
Definition: thermal_model.hh:105
gem5::ThermalResistor::ThermalResistor
ThermalResistor(const Params &p)
ThermalResistor.
Definition: thermal_model.cc:71
gem5::ThermalCapacitor
A ThermalCapacitor is used to model a thermal capacitance between two thermal domains.
Definition: thermal_model.hh:89
gem5::ArmISA::i
Bitfield< 7 > i
Definition: misc_types.hh:66
gem5::ThermalModel::resistors
std::vector< ThermalResistor * > resistors
Definition: thermal_model.hh:168
gem5::ThermalModel::nodes
std::vector< ThermalNode * > nodes
Definition: thermal_model.hh:173
gem5::ThermalResistor::Params
ThermalResistorParams Params
Definition: thermal_model.hh:66
gem5::ThermalReference::ThermalReference
ThermalReference(const Params &p)
ThermalReference.
Definition: thermal_model.cc:56
gem5::ThermalModel::startup
void startup() override
startup() is the final initialization call before simulation.
Definition: thermal_model.cc:180
gem5::ThermalCapacitor::node1
ThermalNode * node1
Definition: thermal_model.hh:107
gem5::LinearSystem
Definition: linear_solver.hh:111
gem5::Temperature::fromKelvin
static Temperature fromKelvin(double _value)
Definition: temperature.cc:44
gem5::ThermalModel::stepEvent
EventFunctionWrapper stepEvent
Stepping event to update the model values.
Definition: thermal_model.hh:177
gem5::ThermalCapacitor::Params
ThermalCapacitorParams Params
Definition: thermal_model.hh:92
sim_object.hh
gem5::ThermalResistor::_resistance
const double _resistance
Definition: thermal_model.hh:79
gem5::ArmISA::d
Bitfield< 9 > d
Definition: misc_types.hh:63
gem5::MipsISA::p
Bitfield< 0 > p
Definition: pra_constants.hh:326
statistics.hh
gem5::ThermalModel::ThermalModel
ThermalModel(const Params &p)
ThermalModel.
Definition: thermal_model.cc:145
gem5::ThermalNode
A ThermalNode is used to connect thermal entities, such as resistors, capacitors, references and doma...
Definition: thermal_node.hh:54
gem5::ThermalModel::doStep
void doStep()
Definition: thermal_model.cc:151
gem5::ThermalModel::references
std::vector< ThermalReference * > references
Definition: thermal_model.hh:166
gem5::LinearEquation
This class describes a linear equation with constant coefficients.
Definition: linear_solver.hh:55
gem5::ThermalReference
A ThermalReference is a thermal domain with fixed temperature.
Definition: thermal_model.hh:114
gem5::SimObject
Abstract superclass for simulation objects.
Definition: sim_object.hh:146
gem5::ArmISA::c
Bitfield< 29 > c
Definition: misc_types.hh:53
thermal_domain.hh
gem5::Temperature::toKelvin
constexpr double toKelvin() const
Definition: temperature.hh:68
gem5::ThermalCapacitor::node2
ThermalNode * node2
Definition: thermal_model.hh:107
gem5::ThermalResistor::node1
ThermalNode * node1
Definition: thermal_model.hh:81
gem5::ThermalModel::capacitors
std::vector< ThermalCapacitor * > capacitors
Definition: thermal_model.hh:167
name
const std::string & name()
Definition: trace.cc:49
gem5::ClockedObject
The ClockedObject class extends the SimObject with a clock and accessor functions to relate ticks to ...
Definition: clocked_object.hh:234
gem5::ThermalResistor
A ThermalResistor is used to model a thermal resistance between two thermal domains.
Definition: thermal_model.hh:63
gem5::ThermalNode::isref
bool isref
Definition: thermal_node.hh:60
linear_solver.hh
gem5::ThermalModel::entities
std::vector< ThermalEntity * > entities
Definition: thermal_model.hh:170
gem5::ArmISA::n
Bitfield< 31 > n
Definition: misc_types.hh:455
gem5::ThermalDomain
A ThermalDomain is used to group objects under that operate under the same temperature.
Definition: thermal_domain.hh:61
gem5::PowerISA::eq
Bitfield< 29 > eq
Definition: misc.hh:53
gem5::ThermalModel::getTemperature
Temperature getTemperature() const
Definition: thermal_model.cc:241
gem5::ThermalModel::addDomain
void addDomain(ThermalDomain *d)
Definition: thermal_model.cc:213
clocked_object.hh
gem5::ThermalReference::Params
ThermalReferenceParams Params
Definition: thermal_model.hh:117
gem5::ThermalNode::temp
Temperature temp
Definition: thermal_node.hh:61
gem5::ThermalModel::addResistor
void addResistor(ThermalResistor *r)
Definition: thermal_model.cc:234
gem5::MipsISA::r
r
Definition: pra_constants.hh:98
gem5::ThermalModel::_step
const double _step
Step in seconds for thermal updates.
Definition: thermal_model.hh:180
gem5::ClockedObject::Params
ClockedObjectParams Params
Parameters of ClockedObject.
Definition: clocked_object.hh:240
gem5::ThermalResistor::node2
ThermalNode * node2
Definition: thermal_model.hh:81
gem5
Reference material can be found at the JEDEC website: UFS standard http://www.jedec....
Definition: decoder.cc:40
gem5::ThermalCapacitor::getEquation
LinearEquation getEquation(ThermalNode *tn, unsigned n, double step) const override
Definition: thermal_model.cc:112
gem5::ThermalNode::id
int id
Definition: thermal_node.hh:59
gem5::ThermalCapacitor::ThermalCapacitor
ThermalCapacitor(const Params &p)
ThermalCapacitor.
Definition: thermal_model.cc:106

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