Re: [RFC PATCH] slub: RFC: Improving SLUB performance with 38% on NO-PREEMPT

On Thu, 2015-06-04 at 12:31 +0200, Jesper Dangaard Brouer wrote:

This patch improves performance of SLUB allocator fastpath with 38% by
avoiding the call to this_cpu_cmpxchg_double() for NO-PREEMPT kernels.

Reviewers please point out why this change is wrong, as such a large
improvement should not be possible ;-)

I am not sure if anyone already answered, but the cmpxchg_double()
is needed to avoid the ABA problem.

This is the whole point using tid _and_ freelist

Preemption is not the only thing that could happen here, think of
interrupts.



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