Messages in this thread | | | Date | Mon, 31 Aug 2009 21:07:10 +0900 (JST) | Subject | Re: [RFC][PATCH 4/5] memcg: per-cpu charge stock | From | "KAMEZAWA Hiroyuki" <> |
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Balbir Singh wrote: > * KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2009-08-28 > 13:27:06]: > >> >> For avoiding frequent access to res_counter at charge, add per-cpu >> local charge. Comparing with modifing res_coutner (with percpu_counter), >> this approach >> Pros. >> - we don't have to touch res_counter's cache line >> - we don't have to chase res_counter's hierarchy >> - we don't have to call res_counter function. >> Cons. >> - we need our own code. >> >> Considering trade-off, I think this is worth to do. > > I prefer the other part due to > > 1. Code reuse (any enhancements made will benefit us) > 2. Custom batching that can be done easily > 3. Remember hierarchy is explicitly enabled and we've documented that > it is expensive
Hmm. the important point is we don't touch res_counter's cacheline in fast path. And if we don't use memcg's percpu counter, more cacheline/TLB will be necesary. (I think percpu counter is slow.) plz rewrite memcg's percpu counter by youself if you want something generic.
I can't understand what you mention by (3).
Thanks, -Kame
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