Hi, (I send this yesterday already to LKML, so sorry if you receive this twice),
on Intel X3220 CPU based systems (4 physical cores) I came across the following thing (Debian etch, with vanilla kernel 2.6.25.9): starting the following: $ screen -d -m stress -c 2 $ nice -19 screen -d -m stress -c 4 This causes two cores to be 100% busy in user state and one core to be busy in 100% nice state. However, the remaining core is idle. Even watching it over longer stretches of time, the situation remains static. I guess it's a kernel misconfiguration on my part (config available here: https://n0.aei.uni-hannover.de/linux/kernel/config-2.6.25.9-nodes ), but if not could this be a scheduling bug? Thanks for any hint Cheers Carsten PS: In the mean time we have made similar tests on a dual CPU, dual core opteron machine with the same results (on a different kernel, 2.6.24.x). Most bizarre was this result (thanks Steffen!): 6 jobs with nice 19, one with nice 0: Core 1: 100% with nice 0 Core 2: 100% with single nice 19 Core 3: 2*50% (nice 19) Core 4: 3*33% (nice 19) That's definitely something I would not expect. _______________________________________________ Beowulf mailing list, [email protected] To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
