Messages in this thread | | | Date | Wed, 3 Mar 2010 17:59:26 +0100 | From | Fabio Checconi <> | Subject | Re: [PATCH 2/3] sched: enforce per-cpu utilization limits on runtime balancing |
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> 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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