Messages in this thread | | | Date | Fri, 22 Nov 2013 12:33:00 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 3/7] idle, thermal, acpi: Remove home grown idle implementations |
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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.
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