Re: [RFC 2.6.11-rc2-mm2 0/7] mm: manual page migration -- overview II

[Ray Bryant <raybry@sgi.com>]

Paul Jackson wrote:
>>
>>You have to walk to full node mapping for each array, but
>>even with hundreds of nodes that should not be that costly
> 
> 
> I presume if you knew that the job only had pages on certain nodes,
> perhaps due to aggressive use of cpusets, that you would only have to
> walk those nodes, right?
> 
I don't think Andi was proposing you have to search all of the pages
on a node.  I think that the idea was that the (count, old_nodes, new_nodes)
parameters would have to be converted to a full node_map such as is done
in the patch (let's call it "sample code") that I sent out with the
overview that started this whole discussion.  node_map[] is MAX_NUMNODES
in length, and node_map[i] gives the node where pages on node i should be
migrated to, or is -1 if we are not migrating pages on this node.

Since we have extended the interface to support -1 as a possible value for
the old_nodes array [and it matches any old node], then in that case we
would make node_map[i]=new_node for all values of i.

-- 
Best Regards,
Ray
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                   Ray Bryant
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