2014-12-18 0:36 GMT+09:00 Christoph Lameter <cl@xxxxxxxxx>: > On Wed, 17 Dec 2014, Joonsoo Kim wrote: > >> Ping... and I found another way to remove preempt_disable/enable >> without complex changes. >> >> What we want to ensure is getting tid and kmem_cache_cpu >> on the same cpu. We can achieve that goal with below condition loop. >> >> I ran Jesper's benchmark and saw 3~5% win in a fast-path loop over >> kmem_cache_alloc+free in CONFIG_PREEMPT. >> >> 14.5 ns -> 13.8 ns >> >> See following patch. > > Good idea. How does this affect the !CONFIG_PREEMPT case? One more this_cpu_xxx makes fastpath slow if !CONFIG_PREEMPT. Roughly 3~5%. We can deal with each cases separately although it looks dirty. #ifdef CONFIG_PREEMPT XXX #else YYY #endif Thanks. -- 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>