On Thu, 15 Jan 2015, Andrew Morton wrote: > > I saw roughly 5% win in a fast-path loop over kmem_cache_alloc/free > > in CONFIG_PREEMPT. (14.821 ns -> 14.049 ns) > > I'm surprised. preempt_disable/enable are pretty fast. I wonder why > this makes a measurable difference. Perhaps preempt_enable()'s call to > preempt_schedule() added pain? The rest of the fastpath is already highly optimized. That is why something like preempt enable/disable has such a disproportionate effect. -- 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>