From: mquinson Date: Tue, 13 Feb 2007 22:16:29 +0000 (+0000) Subject: Update 'Where is the get_host_load function hidden in MSG?' according to the last... X-Git-Tag: v3.3~2216 X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/commitdiff_plain/5629ee08839a59133fbc0b00f4f6f1b4b098334e Update 'Where is the get_host_load function hidden in MSG?' according to the last thread on -user git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/simgrid/simgrid/trunk@3143 48e7efb5-ca39-0410-a469-dd3cf9ba447f --- diff --git a/doc/FAQ.doc b/doc/FAQ.doc index 6975d0de46..0fd24d44c5 100644 --- a/doc/FAQ.doc +++ b/doc/FAQ.doc @@ -480,12 +480,20 @@ even take the currently running tasks into account. In some SURF models, communications have an influence on computational power. Should it be taken into account too? -So, we decided not to include such a function into MSG and let people do it -thereselves so that they get the value matching exactly what they mean. One -possibility is to run active measurement as in next code snippet. It is very -close from what you would have to do out of the simulator, and thus gives -you information that you could also get in real settings to not hinder the -realism of your simulation. +First of all, it's near to impossible to predict the load beforehands in the +simulator since it depends on too much parameters (background load +variation, bandwidth sharing algorithmic complexity) some of them even being +not known beforehands (other task starting at the same time). So, getting +this information is really hard (just like in real life). It's not just that +we want MSG to be as painful as real life. But as it is in some way +realistic, we face some of the same problems as we would face in real life. + +How would you do it for real? The most common option is to use something +like NWS that performs active probes. The best solution is probably to do +the same within MSG, as in next code snippet. It is very close from what you +would have to do out of the simulator, and thus gives you information that +you could also get in real settings to not hinder the realism of your +simulation. \verbatim double get_host_load() {