X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/7387c7850c108e54781753c306fce5977847e86f..6a08055e39d84cfc950ebd85f7d7f15dc87a777f:/doc/FAQ.doc diff --git a/doc/FAQ.doc b/doc/FAQ.doc index 1cdeef6ae3..ee25a4349b 100644 --- a/doc/FAQ.doc +++ b/doc/FAQ.doc @@ -1367,7 +1367,38 @@ annotate Tiers-generated topologies. This perl-script is in tools/platform_generation/ directory of the SVN. Dinda et Al. released a very comparable tool, and called it GridG. -\subsubsection faq_SURF_dynamic Expressing dynamic resource availability in platform files +\subsubsection faq_SURF_multicore Modeling multi-core resources + +There is currently no native support for multi-core or SMP machines in +SimGrid. We are currently working on it, but coming up with the right +model is very hard: Cores share caches and bus to access memory and +thus interfere with each others. Memory contention is a crucial +component of multi-core modeling. + +In the meanwhile, some user-level tricks can reveal sufficient for +you. For example, you may model each core by a CPU and add some very +high speed links between them. This complicates a bit the user code +since you have to remember that when you assign something to a (real) +host, it can be any of the (fake) hosts representing the cores of a +given machine. For that, you can use the prop tag of the XML files as +follows. Your code should then look at the ‘machine’ property +associated with each workstation, and run parallel tasks over all +cores of the machine. + +\verbatim + + + + + + + + + + +\endverbatim + +\subsubsection faq_SURF_dynamic Modeling dynamic resource availability A nice feature of SimGrid is that it enables you to seamlessly have resources whose availability change over time. When you build a