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. If you can I can add more WARN_ON()s in play_idle() to ensure we're not called while holding any RCU locks. -- 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/