Bug 24742

Summary:	Core i7 loses its multithreading capability after suspend
Product:	Power Management	Reporter:	Keivan Moradi (k.moradi)
Component:	Hibernation/Suspend	Assignee:	power-management_other
Status:	CLOSED CODE_FIX
Severity:	normal	CC:	rjw
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	2.6.34 r12 gentoo-sources	Subsystem:
Regression:	No	Bisected commit-id:
Bug Depends on:
Bug Blocks:	7216

Description Keivan Moradi 2010-12-12 14:31:29 UTC

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

Comment 1 Rafael J. Wysocki 2011-01-16 22:45:54 UTC

Does the problem still occur with 2.6.37?

Comment 2 Keivan Moradi 2011-01-17 00:25:16 UTC

problem solved in 2.6.36