further ignorable cleanups

[simgrid.git] / src / surf / plugins / energy.cpp

diff --git a/src/surf/plugins/energy.cpp b/src/surf/plugins/energy.cpp
index 3d7c8a8..4808523 100644 (file)
--- a/src/surf/plugins/energy.cpp
+++ b/src/surf/plugins/energy.cpp
@@ -1,17 +1,16 @@
-/* Copyright (c) 2010, 2012-2015. The SimGrid Team.
- * All rights reserved.                                                     */
+/* Copyright (c) 2010, 2012-2016. The SimGrid Team. All rights reserved.    */
 
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
 
-#include <utility>
-
 #include "simgrid/plugins/energy.h"
 #include "simgrid/simix.hpp"
 #include "src/surf/plugins/energy.hpp"
 #include "src/surf/cpu_interface.hpp"
 #include "src/surf/virtual_machine.hpp"
 
+#include <utility>
+
 /** @addtogroup SURF_plugin_energy
 
 
@@ -78,7 +77,7 @@ void HostEnergy::update()
     cpu_load = lmm_constraint_get_usage(surf_host->cpu_->getConstraint()) / surf_host->cpu_->getPstateSpeedCurrent();
 
   /** Divide by the number of cores here **/
-  cpu_load /= surf_host->cpu_->getCoreCount();
+  cpu_load /= surf_host->cpu_->coreCount();
 
   if (cpu_load > 1) // A machine with a load > 1 consumes as much as a fully loaded machine, not more
     cpu_load = 1;
@@ -151,11 +150,29 @@ double HostEnergy::getCurrentWattsValue(double cpu_load)
   double max_power     = 0;
   double power_slope   = 0;
 
-  if (cpu_load != 0) { /* Something is going on, the machine is not idle */
+  if (cpu_load > 0) { /* Something is going on, the machine is not idle */
     double min_power = range.min;
     double max_power = range.max;
-    double power_slope = max_power - min_power;
-    current_power = min_power + cpu_load * power_slope;
+
+    /**
+     * 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;