Messages in this thread | | | Date | Wed, 13 Aug 2014 05:48:18 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH v5 tip/core/rcu 15/16] rcu: Make RCU-tasks wait for idle tasks |
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On Wed, Aug 13, 2014 at 10:12:15AM +0200, Peter Zijlstra wrote: > On Mon, Aug 11, 2014 at 03:49:04PM -0700, Paul E. McKenney wrote: > > From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> > > > > Because idle-task code may need to be patched, RCU-tasks need to wait > > for idle tasks to schedule. This commit therefore detects this case > > via context switch. Block CPU hotplug during this time to avoid sending > > IPIs to offline CPUs. > > > > Note that checking for changes in the dyntick-idle counters is tempting, > > but wrong. The reason that it is wrong is that a interrupt or NMI can > > increment these counters without necessarily allowing the idle tasks to > > make any forward progress. > > I'm going to NAK this.. with that rcu_idle patch I send there's > typically only a single idle function thats out of bounds and if its > more it can be made that with a bit of tlc to the cpuidle driver in > question. > > This needs _FAR_ more justification than a maybe and a want.
Peter, your patch might be a good start, but I didn't see any reaction from Steven or Masami and it did only x86.
Thanx, Paul
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