- auto range = power_range_watts_list.at(host->pstate());
- double min_power = range.first;
- double max_power = range.second;
- double power_slope = max_power - min_power;
- double current_power = min_power + cpu_load * power_slope;
+ auto range = power_range_watts_list.at(host->pstate());
+ double current_power = 0;
+ double min_power = 0;
+ double max_power = 0;
+ double power_slope = 0;
+
+ if (cpu_load > 0) { /* Something is going on, the machine is not idle */
+ double min_power = range.min;
+ double 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)
+ */
+ double power_slope;
+ int coreCount = host->coreCount();
+ double coreReciprocal = static_cast<double>(1) / static_cast<double>(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! */
+ current_power = range.idle;
+ }