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    SubjectRe: [RFC] Make need_resched() return true when rcu_urgent_qs requested
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    On Mon, 2018-07-09 at 13:42 -0700, Paul E. McKenney wrote:
    > On Mon, Jul 09, 2018 at 09:35:38PM +0100, David Woodhouse wrote:
    > > 
    > > 
    > > On Mon, 2018-07-09 at 13:34 -0700, Paul E. McKenney wrote:
    > > > 
    > > > So here are the possible code paths when .rcu_urgent_qs is set to true:
    > > > 
    > > > 1.      A context switch will record the quiescent state and clear
    > > >         .rcu_urgent_qs.  (The failure to do the clearing in current -rcu
    > > >         for PREEMPT builds is a performance bug that I need to fix.)
    > > 
    > > What if there's nothing else runnable and there is no actual context
    > > switch?
    >
    > The scheduler invokes rcu_note_context_switch() before looking to see
    > if there really will or won't be a context switch.
    >
    > I am sure that Peter will correct me if I am confused on this point.  ;-)

    Ah, OK. Yes, that looks correct. Thanks.

    I'll give your patch a spin tomorrow, unless Marius beats me to it.[unhandled content-type:application/x-pkcs7-signature]
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