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Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics

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On Tue, Sep 15, 2015 at 07:09:22AM -0700, Paul E. McKenney wrote:
> On Tue, Sep 15, 2015 at 02:48:00PM +0200, Peter Zijlstra wrote:
> > On Tue, Sep 15, 2015 at 05:41:42AM -0700, Paul E. McKenney wrote:
> > > > Never mind, the PPC people will implement this with lwsync and that is
> > > > very much not transitive IIRC.
> > > 
> > > I am probably lost on context, but...
> > > 
> > > It turns out that lwsync is transitive in special cases.  One of them
> > > is a series of release-acquire pairs, which can extend indefinitely.
> > > 
> > > Does that help in this case?
> > 
> > Probably not, but good to know. I still don't think we want to rely on
> > ACQUIRE/RELEASE being transitive in general though.
> 
> OK, I will bite...  Why not?

It would mean us reviewing all archs (again) and documenting it I
suppose. Which is of course entirely possible.

That said, I don't think the case at hand requires it, so lets postpone
this for now ;-)
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[PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Davidlohr Bueso <dave@stgolabs.net> - 2015-09-14 09:40 +0200
  Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Peter Zijlstra <peterz@infradead.org> - 2015-09-14 14:40 +0200
    Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Davidlohr Bueso <dave@stgolabs.net> - 2015-09-14 23:10 +0200
      Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Peter Zijlstra <peterz@infradead.org> - 2015-09-15 12:00 +0200
        Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Peter Zijlstra <peterz@infradead.org> - 2015-09-15 12:00 +0200
          Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Peter Zijlstra <peterz@infradead.org> - 2015-09-15 14:50 +0200
            Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-09-15 16:20 +0200
              Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Peter Zijlstra <peterz@infradead.org> - 2015-09-15 16:20 +0200
                Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-09-15 17:40 +0200
                Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Peter Zijlstra <peterz@infradead.org> - 2015-09-15 18:40 +0200
                Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-09-15 19:10 +0200
                Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-09-18 23:50 +0200
                Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Martin Schwidefsky <schwidefsky@de.ibm.com> - 2015-09-21 11:30 +0200
          Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-09-15 14:50 +0200
          Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Davidlohr Bueso <dave@stgolabs.net> - 2015-09-15 22:00 +0200
            Re: [PATCH -tip 2/3] sched/wake_q: Relax to acquire semantics Peter Zijlstra <peterz@infradead.org> - 2015-09-16 11:10 +0200

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