Re: [PATCH] mm, mempolicy: clean up __GFP_THISNODE confusion in policy_zonelist

From: Vlastimil Babka
Date: Fri Oct 21 2016 - 08:08:29 EST

On 10/21/2016 01:34 PM, Aneesh Kumar K.V wrote:
Michal Hocko <mhocko@xxxxxxxxxx> writes:

For both MPOL_PREFERED and MPOL_INTERLEAVE we pick the zone list from
the node other than the current running node. Why don't we do that for
MPOL_BIND ?ie, if the current node is not part of the policy node mask
why are we not picking the first node from the policy node mask for

For MPOL_PREFERED and MPOL_INTERLEAVE we got some explicit preference of nodes, so it makes sense that the nodes in the zonelist we pick are ordered by the distance from that node, regardless of current node.

For MPOL_BIND, we don't have preferences but restrictions. If the current cpu is from a node within the restriction, then great. If it's not, finding a node according to distance from current cpu is probably less arbitrary than by distance from the node that happens to have the lowest id in the node mask?


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