Hello, Peter. On Fri, Jul 20, 2012 at 06:39:51PM +0200, Peter Zijlstra wrote: > On Tue, 2012-07-17 at 10:12 -0700, Tejun Heo wrote: > > Currently, workqueue destroys all workers for offline CPUs unless > > there are lingering work items. > > _that_ is the root of all ugly in that thing. I still find it utterly > insane you can create 'per-cpu' workqueues and then violate the per-cpu > property with hotplug and get your work ran on a different CPU.
Let's talk about this part in the other reply you made. > It should be a hard error to use queue_work_on() and then run the work > on a different cpu. Yet somehow this isn't so. Ooh, yeah, I agree. That's next on the wq to-do list. The problem is that queue_work() is implemented in terms of queue_work_on(). In most cases, the local binding serves as locality optimization than anything else. There are use cases where affinity is required for correctness. The assumption was that they should flush during CPU_DOWN but it probably will be much better to require users which need CPU affinity to always use queue_work_on() - instead of implicit local affinity from queue_work() - and flush them automatically from wq callback. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
