Messages in this thread | | | Subject | Re: [PATCH] memcg: remove unneeded preempt_disable | From | Peter Zijlstra <> | Date | Thu, 25 Aug 2011 20:49:32 +0200 |
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On Thu, 2011-08-25 at 13:46 -0500, Christoph Lameter wrote: > > RISC cpus have instruction to construct complex atomic actions by the cpu > as I have shown before for ARM.
Right, but it only makes sense if the whole thing remains cheaper than the trivial implementation already available.
For instance, the ARM LL/SC constraints pretty much mandate we do preempt_disable()/preempt_enable() around them, at which point the point of doing LL/SC is gone (except maybe for the irqsafe_this_cpu_* stuff).
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