Messages in this thread | | | Date | Wed, 19 Feb 2014 13:45:14 -0800 (PST) | From | David Rientjes <> | Subject | Re: ppc: RECLAIM_DISTANCE 10? |
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On Wed, 19 Feb 2014, Michal Hocko wrote:
> Interesting. So is the PPC NUMA basically about local vs. very distant?
The point is that it's impossible to tell how distant they are from one NUMA domain to the next NUMA domain.
> Should REMOTE_DISTANCE reflect that as well? Or can we have > distance < REMOTE_DISTANCE and it would still make sense to have > zone_reclaim enabled? >
Ppc doesn't want to allocate in a different NUMA domain unless required, the latency of a remote access is too high. Everything that isn't in the same domain has a distance >10 and is setup as 2^(domain hops) * 10. We don't have the ability like with a SLIT to define remote nodes to have local latency vs remote or costly latency so the safe setting is a RECLAIM_DISTANCE of 10.
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