Jens Axboe <[email protected]> writes: > On 2012-12-03 19:53, Jeff Moyer wrote: >> Hi, >> >> In realtime environments, it may be desirable to keep the per-bdi >> flusher threads from running on certain cpus. This patch adds a >> cpu_list file to /sys/class/bdi/* to enable this. The default is to tie >> the flusher threads to the same numa node as the backing device (though >> I could be convinced to make it a mask of all cpus to avoid a change in >> behaviour). > > Looks sane, and I think defaulting to the home node is a sane default. > One comment: > >> + ret = cpulist_parse(buf, newmask); >> + if (!ret) { >> + spin_lock(&bdi->wb_lock); >> + task = wb->task; >> + if (task) >> + get_task_struct(task); >> + spin_unlock(&bdi->wb_lock); > > bdi->wb_lock needs to be bh safe. The above should have caused lockdep > warnings for you.
No lockdep complaints. I'll double check that's enabled (but I usually have it enabled...). >> @@ -437,6 +488,14 @@ static int bdi_forker_thread(void *ptr) >> spin_lock_bh(&bdi->wb_lock); >> bdi->wb.task = task; >> spin_unlock_bh(&bdi->wb_lock); >> + mutex_lock(&bdi->flusher_cpumask_mutex); >> + ret = set_cpus_allowed_ptr(task, >> + bdi->flusher_cpumask); >> + mutex_unlock(&bdi->flusher_cpumask_mutex); > > It'd be very useful if we had a kthread_create_cpu_on_cpumask() instead > of a _node() variant, since the latter could easily be implemented on > top of the former. But not really a show stopper for the patch... Hmm, if it isn't too scary, I might give this a try. Thanks! Jeff -- 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/
