Messages in this thread | | | Date | Wed, 27 Feb 2008 14:00:42 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [RFC][PATCH] page reclaim throttle take2 |
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On Wed, 27 Feb 2008 13:45:18 +0900 KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
> Hi > > > One more thing, I would request you to add default heuristics (number of > > reclaimers), based on the number of cpus in the system. Letting people tuning it > > is fine, but defaults should be related to number of cpus, nodes and zones on > > the system. Zones can be reaped in parallel per node and cpus allow threads to > > run in parallel. So please use that to come up with good defaults, instead of a > > number like "3". > > I don't think so. > all modern many cpu machine stand on NUMA. > it mean following, > - if cpu increases, then zone increases, too. > > if default value increase by #cpus, lock contension dramatically increase > on large numa. > > Have I overlooked anything? > > How about adding something like.. == CONFIG_SIMULTANEOUS_PAGE_RECLAIMERS int default 3 depends on DEBUG help This value determines the number of threads which can do page reclaim in a zone simultaneously. If this is too big, performance under heavy memory pressure will decrease. If unsure, use default. ==
Then, you can get performance reports from people interested in this feature in test cycle.
Thanks, -Kame
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