Messages in this thread | | | Date | Thu, 18 Dec 2014 23:38:09 +0900 | Subject | Re: [PATCH 0/7] slub: Fastpath optimization (especially for RT) V1 | From | Joonsoo Kim <> |
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2014-12-18 0:36 GMT+09:00 Christoph Lameter <cl@linux.com>: > 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.
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