Re: [PATCH] SLUB use cmpxchg_local

[Christoph Lameter]

On Tue, 21 Aug 2007, Mathieu Desnoyers wrote:

> - Changed smp_rmb() for barrier(). We are not interested in read order
>   across cpus, what we want is to be ordered wrt local interrupts only.
>   barrier() is much cheaper than a rmb().

But this means a preempt disable is required. RT users do not want that.
Without preemption the processor can be moved after c has been determined.
That is why the smp_rmb() is there.
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