Re: [PATCH RFC tip/core/rcu 11/11] rcu: move TREE_RCU from softirqto kthread

[Christoph Lameter]

On Wed, 23 Feb 2011, Paul E. McKenney wrote:

> These do introduce redundant preempt_disable()/preempt_enable() calls, but
> this is not on a fastpath, so should be OK, and the improved readability
> is certainly nice.  The read and the write do need to happen on the same
> CPU, FWIW.

this_cpu_xxx only use preempt_enable/disable() on platforms that do not
support per cpu atomic instructions. On x86 no preempt enable/disable will
be inserted.

You can also use the __this_cpu_xxx operations which never add preempt
disable/enable because they expect the caller to deal with preemption.
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