On Fri, Nov 22, 2013 at 12:33:00PM +0100, Peter Zijlstra wrote: > On Thu, Nov 21, 2013 at 08:20:36PM -0800, Paul E. McKenney wrote: > > The 6ms to 25ms range should be just fine as far as normal RCU grace > > periods are concerned. However, it does mean that expedited grace > > periods could be delayed: They normally take a few tens of microseconds, > > but if they were unlucky enough to show up during an idle injection, > > they would be magnified by two to three orders of magnitude, which is > > not pretty. > > > > Hence my suggestion of hooking into RCU on idle-injection start and end > > so that RCU considers that time period to be idle. Just like it does > > for user-mode execution on NO_HZ_FULL kernels, so I still don't see this > > approach to be a problem. I must confess that I still don't understand > > what Arjan doesn't like about it. > > Using these patches it would indeed use the RCU idle machinery as per > the normal idle path.
OK, sorry for my confusion! > If you can I can add more WARN_ON()s in play_idle() to ensure we're not > called while holding any RCU locks. An rcu_sleep_check() or something similar, please! Thanx, Paul -- 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/