On Thu, Oct 10, 2013 at 09:43:55AM -0700, Andrew Morton wrote: > > But we would like to remove stomp machine from > > CPU hotplug. > > We do? That's news. It wasn't mentioned in the changelog and should > have been. Why?
It would be an unrelated change to this and unrelated to the reasons as to why I want a faster get_online_cpus(). > > Why prevent all CPUs from running when we want to remove > > one? > > So get_online_cpus() goes away. Nothing is more scalable than nothing! Very much agreed; now stop_machine() wouldn't actually work for hotplug because it will instantly preempt everybody, including someone who might be in the middle of using per-cpu state of the cpu we're about to remove. The freeze suggestion from Ingo would actually work because we freeze tasks at known good points (userspace and kthread_freeze() points) where we know they're not fiddling with per-cpu state. -- 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/
