http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53292
Bug #: 53292 Summary: multi-threaded (OpenMP) is slower than single-threaded Classification: Unclassified Product: gcc Version: 4.6.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassig...@gcc.gnu.org ReportedBy: f...@hotmail.com Created attachment 27352 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27352 cpp file to compile Hello, The problem is : multi-threaded (OpenMP) is slower than single-threaded Test has been ran several times successively. ChunkSize imposed to avoid false sharing. Test ran on Ubuntu 12.04 64 bits / 4Gb RAM / CPU i3 (dual core hyper-threaded : 2 physical cores + 2 logical cores) / gcc version : 4.6.2. Is the problem related to CPU ? i3 hyper-threaded would not be "handled correctly" by g++ or Ubuntu ? Can somebody help or give me clue ? Thanks, FH PS : I am not used to post bug, if this bug has not been posted in the right place feel free to tell me where to post it