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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>