On Tue, Nov 13, 2012 at 12:56:54PM -0500, Nick Bowler wrote: > On 2012-11-13 09:08 -0800, Paul E. McKenney wrote: > > On Tue, Nov 13, 2012 at 09:46:20AM -0500, Nick Bowler wrote: > > > On 2012-11-12 16:49 -0800, Paul E. McKenney wrote: > > > > Hello! > > > > > > > > I know of people using TINY_RCU, TREE_RCU, and TREE_PREEMPT_RCU, but I > > > > have not heard of anyone using TINY_PREEMPT_RCU for whom TREE_PREEMPT_RCU > > > > was not a viable option (in contrast, the people running Linux on > > > > tiny-memmory systems typically use TINY_RCU). Of course, if no one > > > > really needs it, the proper thing to do is to remove it. > > > > > > > > So, if you need TINY_PREEMPT_RCU, please let me know. Otherwise, I will > > > > remove it, probably in the 3.9 timeframe. > > > > > > Yes, I use TINY_PREEMPT_RCU on my UP machines. It is, in fact, the only > > > option. > > > > Suppose that TREE_PREEMPT_RCU was available for !SMP && PREEMPT builds. > > Would that work for you? > > To be honest I don't really know what the difference is, other than what > the help text says, which is: > > [TINY_PREEMPT_RCU] greatly reduces the memory footprint of RCU. > > "Greatly reduced memory footprint" sounds pretty useful... OK, so from your viewpoint, the only possible benefit is smaller memory? How much memory does your device have, if I may ask? > As a side note, I wonder why any of these RCU implementations are > user-seclectable options in the first place? It looks like you will > only ever have one choice, since the dependencies all seem mutually > exclusive: > > TREE_RCU depends on !PREEMPT && SMP > TREE_PREEMPT_RCU depends on PREEMPT && SMP > TINY_RCU depends on !PREEMPT && !SMP > TINY_PREEMPT_RCU depends on PREEMPT && !SMP Inertia on my part. ;-) Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
