On Tue, 08 Oct 2013 12:25:06 +0200 Peter Zijlstra <pet...@infradead.org> wrote:
> The current implementation of get_online_cpus() is global of nature > and thus not suited for any kind of common usage. > > Re-implement the current recursive r/w cpu hotplug lock such that the > read side locks are as light as possible. > > The current cpu hotplug lock is entirely reader biased; but since > readers are expensive there aren't a lot of them about and writer > starvation isn't a particular problem. > > However by making the reader side more usable there is a fair chance > it will get used more and thus the starvation issue becomes a real > possibility. > > Therefore this new implementation is fair, alternating readers and > writers; this however requires per-task state to allow the reader > recursion. Obvious question: can't we adapt lglocks for this? It would need the counter in task_struct to permit reader nesting, but what else is needed? -- 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/
