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SubjectRe: [PATCH RFC tip/core/rcu 11/11] rcu: move TREE_RCU from softirq to kthread
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On Wed, 2011-02-23 at 20:23 +0100, Peter Zijlstra wrote:
> On Wed, 2011-02-23 at 13:19 -0600, Christoph Lameter wrote:
>
> > this_cpu_inc is already percpu atomic. On x86 it is an instruction that
> > cannot be interrupted nor preempted while in progress.
>
> On x86, yes, but is this true for all architectures? I guess the
> fallback is implemented with local_irq_disable() which might be good
> enough for some but not for NMI usage.

IIRC, those archs that can not do an atomic inc or cmpxchg have NMIs
that are basically "The Sh*t hit the fan, bail". Where the NMIs are used
only to dump out the state of the system and not something more advanced
that can do things like profiling.

-- Steve




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