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SubjectRe: [PATCH 2/3] sched: enforce per-cpu utilization limits on runtime balancing
> From: Peter Zijlstra <peterz@infradead.org>
> Date: Thu, Feb 25, 2010 09:28:22PM +0100
>
> On Tue, 2010-02-23 at 19:56 +0100, Fabio Checconi wrote:
> > + /*
> > + * Make sure that before restarting balancing everyone
> > + * sees the new free bandwidth.
> > + */
> > + smp_wmb();
>
> You cannot order something on its own, barriers come in pairs, where is
> his?

It was coupled with the acquire barrier implied by the spin_lock(rt_b)
in the balance path, as the other wmb() before starting the reset (more
details on the reply about this last barrier, as per your comment they
can be removed).


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