On Tue, Jun 17, 2014 at 10:37:17AM -0700, Paul E. McKenney wrote: > Oh, and to answer the implicit question... A properly configured 4096-CPU > system will have two funnel levels, with 64 nodes at the leaf level > and a single node at the root level. If the system is not properly > configured, it will have three funnel levels. The maximum number of > funnel levels is four, which would handle more than four million CPUs > (sixteen million if properly configured), so we should be good. ;-) > > The larger numbers of levels are intended strictly for testing. I set > CONFIG_RCU_FANOUT_LEAF=2 and CONFIG_RCU_FANOUT=2 on a 16-CPU system just > to make sure that I am testing something uglier than what will be running > in production. A large system should have both of these set to 64, > though this requires also booting with skew_tick=1 as well.
Right, and I think we talked about this before; the first thing one should do is align the RCU fanout masks with the actual machine topology. Because currently they can be all over the place. -- 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/
