This is the energy plugin, enabling to account not only for computation time,
but also for the dissipated energy in the simulated platform.
+To activate this plugin, first call MSG_energy_plugin_init() before your #MSG_init(),
+and then use MSG_host_get_consumed_energy() to retrieve the consumption of a given host.
-The energy consumption of a CPU depends directly of its current load. Specify that consumption in your platform file as
-follows:
+When the host is on, this energy consumption naturally depends on both the
+current CPU load and the host energy profile. According to our measurements,
+the consumption is somehow linear in the amount of cores at full speed,
+with an abnormality when all the cores are idle.
-\verbatim
-<host id="HostA" power="100.0Mf" cores="8">
+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 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">
<prop id="watt_per_state" value="100.0:120.0:200.0" />
<prop id="watt_off" value="10" />
</host>
-\endverbatim
+\endcode
+
+This example gives the following parameters: \b Off is 10 Watts; \b Idle is 100 Watts; \b OneCore 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>4</td><td> 200 Watts</td><td>AllCores value</td></tr>
+</table>
+
+### What if a given core is only at load 50%?
+
+Well, that's 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 the model holds.
-The first property means that when your host is up and running, but without anything to do, it will dissipate 100 Watts.
-If only one care is active, it will dissipate 120 Watts. If it's fully loaded, it will dissipate 200 Watts. If its load is at 50%, then it will dissipate 153.33 Watts.
-The second property means that when your host is turned off, it will dissipate only 10 Watts (please note that these
-values are arbitrary).
+### What if the host has only one core?
-If your CPU is using pstates, then you can provide one consumption interval per pstate.
+In this case, the parameters \b OneCore and \b AllCores are obviously the same.
+Actually, SimGrid expect an energetic profile formated 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.
-\verbatim
-<host id="HostB" power="100.0Mf,50.0Mf,20.0Mf" pstate="0" >
+\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 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">
<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>
-\endverbatim
+\endcode
-That host has 3 levels of performance with the following performance: 100 Mflop/s, 50 Mflop/s or 20 Mflop/s.
-It starts at pstate 0 (ie, at 100 Mflop/s). In this case, you have to specify one interval per pstate in the
-watt_per_state property.
-In this example, the idle consumption is 95 Watts, 93 Watts and 90 Watts in each pstate while the CPU burn consumption
-are at 200 Watts, 170 Watts, and 150 Watts respectively. If only one core is active, this machine consumes 120 / 115 / 110 watts.
+This encodes the following values
+<table>
+<tr><th>pstate</th><th>Performance</th><th>Idle</th><th>OneCore</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>
+</table>
To change the pstate of a given CPU, use the following functions:
#MSG_host_get_nb_pstates(), simgrid#s4u#Host#setPstate(), #MSG_host_get_power_peak_at().
-To simulate the energy-related elements, first call the simgrid#energy#sg_energy_plugin_init() before your #MSG_init(),
-and then use the following function to retrieve the consumption of a given host: MSG_host_get_consumed_energy().
*/
XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_energy, surf, "Logging specific to the SURF energy plugin");
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->cname(), all_power_values_str, host->coreCount());
int i = 0;
for (auto current_power_values_str : all_power_values) {
/* retrieve the power values associated with the current pstate */
std::vector<std::string> current_power_values;
boost::split(current_power_values, current_power_values_str, boost::is_any_of(":"));
- xbt_assert(current_power_values.size() == 3, "Power properties incorrectly defined - "
- "could not retrieve idle, min and max power values for host %s",
- host->cname());
+ if (host->coreCount() == 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->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
+ xbt_assert((current_power_values.at(1)) == (current_power_values.at(2)),
+ "Power properties incorrectly defined for host %s.\n"
+ "The energy profile of mono-cores should be formated as 'Idle:FullSpeed' only.\n"
+ "If you go for a 'Idle:OneCore:AllCores' power profile on mono-cores, then OneCore and AllCores "
+ "must be equal.",
+ host->cname());
+ }
+ } 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->cname());
+ }
/* 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->cname());
- char* msg_min = bprintf("Invalid min value for pstate %d on host %s: %%s", i, host->cname());
- char* msg_max = bprintf("Invalid max value for pstate %d on host %s: %%s", i, host->cname());
+ char* msg_min = bprintf("Invalid OneCore value for pstate %d on host %s: %%s", i, host->cname());
+ char* msg_max = bprintf("Invalid AllCores value for pstate %d on host %s: %%s", i, host->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));
