On Mon, Jun 11, 2007 at 09:36:34AM +0200, Ingo Molnar wrote: > > * Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote: > > > 2.6.21.4-rt12 boots on 4-CPU Opteron and passes several hours of > > rcutorture. However, if I simply do "modprobe rcutorture", the kernel > > threads do not spread across the CPUs as I would expect them to, even > > given CFS. Instead, the readers all stack up on a single CPU, and I > > have to use the "taskset" command to spread them out manually. Is > > there some config parameter I am missing out on? > > hm, what affinity do they start out with? Could they all be pinned to > CPU#0 by default? They start off with affinity masks of 0xf on a 4-CPU system. I would expect them to load-balance across the four CPUs, but they stay all on the same CPU until long after I lose patience (many minutes). Since there are eight readers, I use the following commands: taskset -p 3 pid1 taskset -p 3 pid2 taskset -p 6 pid3 taskset -p 6 pid4 taskset -p c pid5 taskset -p c pid6 taskset -p 9 pid7 taskset -p 9 pid8 where the "pidn" are all replaced by the pids of the torture readers. Before I do this, the processes are all sharing a single CPU. After I do this, they are spread reasonably nicely over the CPUs. I do need to allow some migration in order to fully test the realtime RCU variants in the various preemption scenarios. Thanx, Paul - To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
