I hope Ingo will correct me if I am wrong, On 05/31, Mark Hounschell wrote: > > Oleg Nesterov wrote: > > > > So, the main question is: is it possible that one of RT processes/threads > > pins itself > > to some CPU and eats 100% cpu power? > > > > The main process is pinned to a processor(2) with all _non-kernel_ > processes/threads forced over to processor 1. > Any already affinitized processes or kernel threads are left as is. Only user > land stuff is moved. The main process > is for sure _not_ relinquishing it's processor(2) intentionally.
This means that a non-rt kernel thread bound to CPU 2 can't run. In particular, events/2. This means that the problem is not directly connected to floppy.c, any flush_scheduled_work() (or schedule_on_each_cpu()) can't succeed. You can change irq/X/smp_affinity, but smp_apic_timer_interrupt() still can queue work_struct on CPU 2 (for example, mm/slab.c uses per-cpu reap_work). Since events/2 is blocked by the main RT thread, such a work_struct can't be executed, and so flush_scheduled_work() hangs. > All the I/O threads, floppy included, are running > on the other processor(1). During this failure only 1 or 2 of the I/O threads > are actually doing anything. > I assume that what ever is going on in the kernel/floppy driver on behalf of > the floppy thread is being done on processor 1? > Processor 1 has lots of CPU time available. Yes, but see above. flush_scheduled_work() needs a cooperation from events/2 which is bound to CPU 2. If you changed irq/X/smp_affinity, the patch I sent should help, because floppy_work can't be scheduled on CPU 2, but still I don't think it is right to run 100% cpu-bound RT-process. Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
