scheduler: replace migration_thread with cpuhog
in [Kernel]
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From: Oleg Nesterov on 29 Mar 2010 10:10 As I said, personally I like these changes very much. Even if I can't ack them I'd like to add my vote. On 03/17, Tejun Heo wrote: > > int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) > { > ... > + if (migrate_task(p, dest_cpu)) { > + struct migration_arg arg = { p, dest_cpu }; > /* Need help from migration thread: drop lock and wait. */ > - struct task_struct *mt = rq->migration_thread; > - > - get_task_struct(mt); > task_rq_unlock(rq, &flags); > - wake_up_process(rq->migration_thread); > - put_task_struct(mt); > - wait_for_completion(&req.done); > + hog_one_cpu(cpu_of(rq), migration_hog, &arg); Afaics, this is the only change which can make a difference. If we race with cpu_down(), set_cpus_allowed_ptr() can return before the task was actually moved to another CPU. But this seems harmless to me. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Peter Zijlstra on 29 Mar 2010 10:20
On Mon, 2010-03-29 at 15:57 +0200, Oleg Nesterov wrote: > As I said, personally I like these changes very much. Even if I can't ack them > I'd like to add my vote. Well, I like what they do, but I hate the name and I don't like how we end up with two interfaces that do pretty much the same thing, this new hog thing and stopmachine. I much prefer to keep the stopmachine name and make that into a usable interface. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |