Turn on UseNUMA by default when prudent

Thomas Schatzl thomas.schatzl at jku.at
Wed May 30 20:14:09 UTC 2012


On Wed, 2012-05-30 at 11:41 -0700, Igor Veresov wrote:
> Actually UseNUMA should already do what you want. Even if specified on the 
> command line it will switch itself off if there's only one node
> present.

This is another way of doing that, i.e. always enabling UseNUMA anyway
in some way.

I have one question about this: UseNUMA is not disabled if I assign the
VM process to cpus of only one node in a NUMA system. Is this

Sure, this process may benefit from using memory from other nodes still
(e.g. before going out-of-memory), but is it a good idea to do an
madvise(MADV_ADVISE_MANY)/interleave memory across nodes in this
situation by default?

So the recommended VM options would probably leave UseNUMA intentionally
off in that case?

I do not know if there is a way to restrict node memory resources of a


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