From: Christian Heinrich <franz-christian.heinrich@inria.fr>
Date: Wed, 7 Feb 2018 12:54:21 +0000 (+0100)
Subject: [DVFS] Fix load calculation for Dvfs governors
X-Git-Tag: v3.19~214
X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/commitdiff_plain/a3f5e3d6901fbcd1857fb8cc07ad3a54bf244bde?ds=sidebyside

[DVFS] Fix load calculation for Dvfs governors

The HostLoad plugin computes the load as <cores used>/<cores total>.
This means that governors sometimes decide to slow down even though
one or several cores were used because too many cores were unused.
---

diff --git a/src/surf/plugins/host_dvfs.cpp b/src/surf/plugins/host_dvfs.cpp
index 985d0d8c4d..1d7336a30a 100644
--- a/src/surf/plugins/host_dvfs.cpp
+++ b/src/surf/plugins/host_dvfs.cpp
@@ -81,7 +81,8 @@ public:
   {
     double load = sg_host_get_current_load(host);
 
-    if (load > freq_up_threshold) {
+    // FIXME I don't like that we multiply with the getCoreCount() just here...
+    if (load*host->getCoreCount() > freq_up_threshold) {
       host->setPstate(0); /* Run at max. performance! */
       XBT_INFO("Changed to pstate %f", 0.0);
     } else {
@@ -109,7 +110,7 @@ public:
 
   void update()
   {
-    double load = sg_host_get_current_load(host);
+    double load = sg_host_get_current_load(host)*host->getCoreCount();
     int pstate  = host->getPstate();
 
     if (load > freq_up_threshold) {