+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>
+\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%?
+
+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 -->