Oleg Nesterov wrote: > On 06/02, Mark Hounschell wrote: >> Jun 2 16:36:11 harley kernel: ERR!! events/1 flush hang: c201dbc0 >> c201dbc0 10012 10012 >> Jun 2 16:36:11 harley kernel: CURR: 7974 7974 vrsx 93 26 >> Jun 2 16:36:11 harley kernel: wq_barrier_func+0x0/0x8 >> Jun 2 16:36:11 harley kernel: vmstat_update+0x0/0x24 >> Jun 2 16:36:11 harley kernel: ---- >> Jun 2 16:36:11 harley kernel: cache_reap+0x0/0xf4 > > As expected. > > Note that ->nivcsw/->nvcsw doesn't change. There is no "spare time" > on CPU 1, "vrsx" monopolizes CPU. events/1->cache_reap() was preempted > by vrsx, it had no chance to run since then. Note that jobs == 7974 > doesn't change too. I forgot to print cwq->thread->state, but it should > be TASK_RUNNING. It would not be possible to kill vrsx if cache_reap() > stalled. > > I don't think this is a kernel problem, vrsx breaks flush_workqueue(). > Ingo can answer authoritatively, but I think SCHED_RR/SCHED_FIFO were > not designed to be 100% cpu-bound. > > That said, I think it makes sense to get rid of flush_scheduled_work() > in floppy.c. >
Oleg, thanks for your time in diagnosing this. As far as a 100% CPU bound task being a valid thing to do, it has been done for many years on SMP machines. Any kernel limitation on this surely must be considered a bug? Thanks again Regards Mark - 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/
