On my gentoo-linux system (2.6.34-gentoo-sources amd64), with a xeon 5540 (core i7) , each time I resume after the command "pm-suspend" (suspend to RAM), mutlithreading capabilities almost disappear. More specifically, two distinct programs can use 2 distinct cores at full rate, but a single program is limited to only one core (for one instance of a multithreaded program as well as multiple instances of a single threaded program, e.g. "make -j 4" for gcc). So I end up rebooting the system. Any help appreciated!

There are other people have this problem. this is a upstream bug.

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=580901

http://codeme.gotdns.com/2010/04/30/core-i7-on-linux-loses-its-multithreading-capability-after-suspend/

http://superuser.com/questions/136291/core-i7-on-linux-loses-its-multithreading-capability-after-suspend

also these bug reports may be related to this one

https://bugzilla.kernel.org/show_bug.cgi?id=16567

https://bugzilla.kernel.org/show_bug.cgi?id=13885