As a result, our energy model takes 4 parameters:
- @b Idle: instantaneous consumption (in Watt) when your host is up and running, but without anything to do.
- - @b OneCore: instantaneous consumption (in Watt) when only one core is active, at 100%.
+ - @b Epsilon: instantaneous consumption (in Watt) when all cores are at 0 or epsilon%, but not in Idle state.
- @b AllCores: instantaneous consumption (in Watt) when all cores of the host are at 100%.
- @b Off: instantaneous consumption (in Watt) when the host is turned off.
Here is an example of XML declaration:
@code{.xml}
-<host id="HostA" power="100.0Mf" cores="4">
+<host id="HostA" speed="100.0Mf" core="4">
<prop id="watt_per_state" value="100.0:120.0:200.0" />
<prop id="watt_off" value="10" />
</host>
@endcode
-This example gives the following parameters: @b Off is 10 Watts; @b Idle is 100 Watts; @b OneCore is 120 Watts and @b
+Please note that the 'Epsilon' parameter can be omitted in the XML declaration. In that case, the value of 'Epsilon' will
+be the same as 'Idle'.
+
+
+This example gives the following parameters: @b Off is 10 Watts; @b Idle is 100 Watts; @b Epsilon is 120 Watts and @b
AllCores is 200 Watts.
This is enough to compute the consumption as a function of the amount of loaded cores:
<table>
<tr><th>@#Cores loaded</th><th>Consumption</th><th>Explanation</th></tr>
-<tr><td>0</td><td> 100 Watts</td><td>Idle value</td></tr>
-<tr><td>1</td><td> 120 Watts</td><td>OneCore value</td></tr>
-<tr><td>2</td><td> 147 Watts</td><td>linear extrapolation between OneCore and AllCores</td></tr>
-<tr><td>3</td><td> 173 Watts</td><td>linear extrapolation between OneCore and AllCores</td></tr>
+<tr><td>0 (idle)</td><td> 100 Watts</td><td>Idle value</td></tr>
+<tr><td>0 (not idle)</td><td> 120 Watts</td><td>Epsilon value</td></tr>
+<tr><td>1</td><td> 140 Watts</td><td>linear extrapolation between Epsilon and AllCores</td></tr>
+<tr><td>2</td><td> 160 Watts</td><td>linear extrapolation between Epsilon and AllCores</td></tr>
+<tr><td>3</td><td> 180 Watts</td><td>linear extrapolation between Epsilon and AllCores</td></tr>
<tr><td>4</td><td> 200 Watts</td><td>AllCores value</td></tr>
</table>
-### What if a given core is only at load 50%?
-
-This is impossible in SimGrid because we recompute everything each time that the CPU starts or stops doing something.
-So if a core is at load 50% over a period, it means that it is at load 100% half of the time and at load 0% the rest of
-the time, and our model holds.
-
-### What if the host has only one core?
-
-In this case, the parameters @b OneCore and @b AllCores are obviously the same.
-Actually, SimGrid expect an energetic profile formatted as 'Idle:Running' for mono-cores hosts.
-If you insist on passing 3 parameters in this case, then you must have the same value for @b OneCore and @b AllCores.
-
-@code{.xml}
-<host id="HostC" power="100.0Mf" cores="1">
- <prop id="watt_per_state" value="95.0:200.0" /> <!-- we may have used '95:200:200' instead -->
- <prop id="watt_off" value="10" />
-</host>
-@endcode
### How does DVFS interact with the host energy model?
If your host has several DVFS levels (several pstates), then you should give the energetic profile of each pstate level:
@code{.xml}
-<host id="HostC" power="100.0Mf,50.0Mf,20.0Mf" cores="4">
+<host id="HostC" speed="100.0Mf,50.0Mf,20.0Mf" core="4">
<prop id="watt_per_state" value="95.0:120.0:200.0, 93.0:115.0:170.0, 90.0:110.0:150.0" />
<prop id="watt_off" value="10" />
</host>
This encodes the following values
<table>
-<tr><th>pstate</th><th>Performance</th><th>Idle</th><th>OneCore</th><th>AllCores</th></tr>
+<tr><th>pstate</th><th>Performance</th><th>Idle</th><th>Epsilon</th><th>AllCores</th></tr>
<tr><td>0</td><td>100 Mflop/s</td><td>95 Watts</td><td>120 Watts</td><td>200 Watts</td></tr>
<tr><td>1</td><td>50 Mflop/s</td><td>93 Watts</td><td>115 Watts</td><td>170 Watts</td></tr>
<tr><td>2</td><td>20 Mflop/s</td><td>90 Watts</td><td>110 Watts</td><td>150 Watts</td></tr>
class PowerRange {
public:
double idle_;
- double min_;
+ double epsilon_;
double max_;
+ double slope_;
- PowerRange(double idle, double min, double max) : idle_(idle), min_(min), max_(max) {}
+ PowerRange(double idle, double epsilon, double max) : idle_(idle), epsilon_(epsilon), max_(max), slope_(max-epsilon) {}
};
class HostEnergy {
double get_idle_consumption();
double get_watt_min_at(int pstate);
double get_watt_max_at(int pstate);
+ double get_power_range_slope_at(int pstate);
void update();
private:
void init_watts_range_list();
simgrid::s4u::Host* host_ = nullptr;
- /*< List of (min_power,max_power) pairs corresponding to each cpu pstate */
+ /*< List of (idle_power, epsilon_power, max_power) tuple corresponding to each cpu pstate */
std::vector<PowerRange> power_range_watts_list_;
/* We need to keep track of what pstate has been used, as we will sometimes be notified only *after* a pstate has been
if (start_time < finish_time) {
double previous_energy = this->total_energy_;
- double instantaneous_consumption = this->get_current_watts_value();
+ double instantaneous_power_consumption = this->get_current_watts_value();
- double energy_this_step = instantaneous_consumption * (finish_time - start_time);
+ double energy_this_step = instantaneous_power_consumption * (finish_time - start_time);
// TODO Trace: Trace energy_this_step from start_time to finish_time in host->getName()
this->total_energy_ = previous_energy + energy_this_step;
this->last_updated_ = finish_time;
- XBT_DEBUG("[update_energy of %s] period=[%.8f-%.8f]; current speed=%.2E flop/s (pstate %i); total consumption before: consumption change: %.8f J -> added now: %.8f J",
+ XBT_DEBUG("[update_energy of %s] period=[%.8f-%.8f]; current speed=%.2E flop/s (pstate %i); total consumption before: %.8f J -> added now: %.8f J",
host_->get_cname(), start_time, finish_time, host_->pimpl_cpu->get_pstate_peak_speed(this->pstate_), this->pstate_, previous_energy,
energy_this_step);
}
{
xbt_assert(not power_range_watts_list_.empty(), "No power range properties specified for host %s",
host_->get_cname());
- return power_range_watts_list_[pstate].min_;
+ return power_range_watts_list_[pstate].epsilon_;
}
double HostEnergy::get_watt_max_at(int pstate)
return power_range_watts_list_[pstate].max_;
}
+double HostEnergy::get_power_range_slope_at(int pstate)
+{
+ xbt_assert(not power_range_watts_list_.empty(), "No power range properties specified for host %s",
+ host_->get_cname());
+ return power_range_watts_list_[pstate].slope_;
+}
+
/** @brief Computes the power consumed by the host according to the current situation
*
* - If the host is off, that's the watts_off value
else {
cpu_load = host_->pimpl_cpu->get_constraint()->get_usage() / current_speed;
- /** Divide by the number of cores here **/
+ /** Divide by the number of cores here to have a value between 0 and 1 **/
cpu_load /= host_->pimpl_cpu->get_core_count();
if (cpu_load > 1) // A machine with a load > 1 consumes as much as a fully loaded machine, not more
host_was_used_ = true;
}
- /* The problem with this model is that the load is always 0 or 1, never something less.
+ /* @mquinson: The problem with this model is that the load is always 0 or 1, never something less.
* Another possibility could be to model the total energy as
*
* X/(X+Y)*W_idle + Y/(X+Y)*W_burn
*
* where X is the amount of idling cores, and Y the amount of computing cores.
+ *
+ * @Mommessc: I do not think the load is always 0 or 1 anymore.
+ * Moreover, it is not quite clear how the regular model of power consumption (P = Pstatic + load * Pdynamic)
+ * is impacted if we separate the number of idle and working cores.
*/
return get_current_watts_value(cpu_load);
}
return watts_off_;
}
- /* min_power corresponds to the power consumed when only one core is active */
- /* max_power is the power consumed at 100% cpu load */
- auto range = power_range_watts_list_.at(this->pstate_);
+ PowerRange power_range = power_range_watts_list_.at(this->pstate_);
double current_power;
- double min_power;
- double max_power;
- double power_slope;
-
- if (cpu_load > 0) { /* Something is going on, the machine is not idle */
- min_power = range.min_;
- max_power = range.max_;
-
- /**
- * The min_power states how much we consume when only one single
- * core is working. This means that when cpu_load == 1/coreCount, then
- * current_power == min_power.
- *
- * The maximum must be reached when all cores are working (but 1 core was
- * already accounted for by min_power)
- * i.e., we need min_power + (maxCpuLoad-1/coreCount)*power_slope == max_power
- * (maxCpuLoad is by definition 1)
- */
- int coreCount = host_->get_core_count();
- double coreReciprocal = 1.0 / coreCount;
- if (coreCount > 1)
- power_slope = (max_power - min_power) / (1 - coreReciprocal);
- else
- power_slope = 0; // Should be 0, since max_power == min_power (in this case)
-
- current_power = min_power + (cpu_load - coreReciprocal) * power_slope;
- } else { /* Our machine is idle, take the dedicated value! */
- min_power = 0;
- max_power = 0;
- power_slope = 0;
- current_power = range.idle_;
+
+ if (cpu_load > 0)
+ {
+ /**
+ * Something is going on, the host is not idle.
+ *
+ * The power consumption follows the regular model:
+ * P(cpu_load) = Pstatic + Pdynamic * cpu_load
+ * where Pstatic = power_range.epsilon_ and Pdynamic = power_range.slope_
+ * and the cpu_load is a value between 0 and 1.
+ */
+ current_power = power_range.epsilon_ + cpu_load * power_range.slope_;
+ }
+ else
+ {
+ /* The host is idle, take the dedicated value! */
+ current_power = power_range.idle_;
}
- XBT_DEBUG("[get_current_watts] pstate=%i, min_power=%f, max_power=%f, slope=%f", this->pstate_, min_power, max_power, power_slope);
+ XBT_DEBUG("[get_current_watts] pstate=%i, epsilon_power=%f, max_power=%f, slope=%f", this->pstate_, power_range.epsilon_,
+ power_range.max_, power_range.slope_);
XBT_DEBUG("[get_current_watts] Current power (watts) = %f, load = %f", current_power, cpu_load);
return current_power;
std::vector<std::string> all_power_values;
boost::split(all_power_values, all_power_values_str, boost::is_any_of(","));
- XBT_DEBUG("%s: profile: %s, cores: %d", host_->get_cname(), all_power_values_str, host_->get_core_count());
+ XBT_DEBUG("%s: power properties: %s", host_->get_cname(), all_power_values_str);
int i = 0;
for (auto const& current_power_values_str : all_power_values) {
- /* retrieve the power values associated with the current pstate */
+ /* retrieve the power values associated with the pstate i */
std::vector<std::string> current_power_values;
boost::split(current_power_values, current_power_values_str, boost::is_any_of(":"));
- if (host_->get_core_count() == 1) {
- xbt_assert(current_power_values.size() == 2 || current_power_values.size() == 3,
- "Power properties incorrectly defined for host %s."
- "It should be 'Idle:FullSpeed' power values because you have one core only.",
- host_->get_cname());
- if (current_power_values.size() == 2) {
- // In this case, 1core == AllCores
- current_power_values.push_back(current_power_values.at(1));
- } else { // size == 3
- current_power_values[1] = current_power_values.at(2);
- current_power_values[2] = current_power_values.at(2);
- static bool displayed_warning = false;
- if (not displayed_warning) { // Otherwise we get in the worst case no_pstate*no_hosts warnings
- XBT_WARN("Host %s is a single-core machine and part of the power profile is '%s'"
- ", which is in the 'Idle:OneCore:AllCores' format."
- " Here, only the value for 'AllCores' is used.", host_->get_cname(), current_power_values_str.c_str());
- displayed_warning = true;
- }
- }
- } else {
- xbt_assert(current_power_values.size() == 3,
- "Power properties incorrectly defined for host %s."
- "It should be 'Idle:OneCore:AllCores' power values because you have more than one core.",
- host_->get_cname());
+
+ xbt_assert(current_power_values.size() == 2 || current_power_values.size() == 3,
+ "Power properties incorrectly defined for host %s."
+ "It should be 'Idle:AllCores' (or 'Idle:Epsilon:AllCores') power values.",
+ host_->get_cname());
+
+ double idle_power;
+ double epsilon_power;
+ double max_power;
+
+ char* msg_idle = bprintf("Invalid Idle value for pstate %d on host %s: %%s", i, host_->get_cname());
+ char* msg_epsilon = bprintf("Invalid Epsilon value for pstate %d on host %s: %%s", i, host_->get_cname());
+ char* msg_max = bprintf("Invalid AllCores value for pstate %d on host %s: %%s", i, host_->get_cname());
+
+ idle_power = xbt_str_parse_double((current_power_values.at(0)).c_str(), msg_idle);
+ if (current_power_values.size() == 2) // Case: Idle:AllCores
+ {
+ epsilon_power = xbt_str_parse_double((current_power_values.at(0)).c_str(), msg_idle);
+ max_power = xbt_str_parse_double((current_power_values.at(1)).c_str(), msg_max);
}
+ else // Case: Idle:Epsilon:AllCores
+ {
+ epsilon_power = xbt_str_parse_double((current_power_values.at(1)).c_str(), msg_epsilon);
+ max_power = xbt_str_parse_double((current_power_values.at(2)).c_str(), msg_max);
+ }
+
+ XBT_DEBUG("Creating PowerRange for host %s. Idle:%f, Epsilon:%f, AllCores:%f.", host_->get_cname(), idle_power, epsilon_power, max_power);
- /* min_power corresponds to the idle power (cpu load = 0) */
- /* max_power is the power consumed at 100% cpu load */
- char* msg_idle = bprintf("Invalid idle value for pstate %d on host %s: %%s", i, host_->get_cname());
- char* msg_min = bprintf("Invalid OneCore value for pstate %d on host %s: %%s", i, host_->get_cname());
- char* msg_max = bprintf("Invalid AllCores value for pstate %d on host %s: %%s", i, host_->get_cname());
- PowerRange range(xbt_str_parse_double((current_power_values.at(0)).c_str(), msg_idle),
- xbt_str_parse_double((current_power_values.at(1)).c_str(), msg_min),
- xbt_str_parse_double((current_power_values.at(2)).c_str(), msg_max));
+ PowerRange range(idle_power, epsilon_power, max_power);
power_range_watts_list_.push_back(range);
xbt_free(msg_idle);
- xbt_free(msg_min);
+ xbt_free(msg_epsilon);
xbt_free(msg_max);
- i++;
+ ++i;
}
}
} // namespace plugin
"The Energy plugin is not active. Please call sg_host_energy_plugin_init() during initialization.");
return host->extension<HostEnergy>()->get_watt_max_at(pstate);
}
-
+/** @ingroup plugin_energy
+ * @brief Returns the power slope at the given pstate
+ */
+double sg_host_get_power_range_slope_at(sg_host_t host, int pstate)
+{
+ xbt_assert(HostEnergy::EXTENSION_ID.valid(),
+ "The Energy plugin is not active. Please call sg_host_energy_plugin_init() during initialization.");
+ return host->extension<HostEnergy>()->get_power_range_slope_at(pstate);
+}
/** @ingroup plugin_energy
* @brief Returns the current consumption of the host
*/
