Messages in this thread |  | | Date | Tue, 13 Feb 2007 10:26:32 -0800 | From | "Martin J. Bligh" <> | Subject | Re: [RFC] [PATCH] more support for memory-less-node. |
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Andi Kleen wrote: >> I wasn't suggesting having NULL pointers for pgdats, if that's what you >> mean. > > That is what started the original thread at least. Can happen on some > ia64 platforms.
OK, that does seem kind of ugly.
>> Just nodes with no memory in them, the pgdat would still be there. >> pgdat = struct node, except everything's badly named. > > Ok those can happen even on x86-64, mostly because it's possible > to fill up a node early during boot up with bootmem and then > it's effectively empty. > > [there is even still a open bug when this happens on node 0] > > Handling out of memory here of course has to be always done.
Yup, if we just set the "size" of the node to zero, it seems like a natural degenerate case that should be handled anyway.
> Just NULL pointers in core data structures are evil. But I'm glad we > agree here. > > Now if it's better to set up a empty node or use a nearby node > for a memory less cpu can be further discussed. I still think > I lean towards the later.
Just seems kind of ugly and unnecessary, particularly if that memory-less cpu (or IO node) is equidistant from one or more memory-possessing nodes. As long as their zonelist is set up correctly, it should all work fine without that, right?
build_zonelists_node already checks populated_zone() so it looks like it's all set up for that already ...
M.
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