Do we need a "max_order" variable that could be adjusted to some lower value that MAX_ORDER if we find the memory topology doesn't fit insidethe lines?(Your email talks about nodes, but I am asuming that we're actually dealing with per-zone concepts here)
...and ...
But I wonder if a better approach would be to teach ia64 to just throw away the last 1 .. MAX_ORDER-1 pages from the oddball zone?
Assume we've got a machine with a memory configuration: Node 0: 0 ... 4 Gbyte - 1 Node 1: 4 Gbyte ... 16 Gbyte - 1 Assume MAX_ORDER is 8 Gbytes (a single binary, for all of our machines, for maintenance reasons). An allocation of 8 Gbytes should have its chance. Therefore the global MAX_ORDER should not be diminished dynamically. Surely we do not want to throw away 4 Gbytes of memory. The kernel should support that both of the nodes have starting address at 0. Therefore the "node_bootmem_map"-s of both of the nodes include the address range 0 ... 4 Gbyte in the example above. The "node_bootmem_map" of node 1 just happens to contain 0-s in the range of 0 ... 4 Gbyte. A not-in-use level of the buddy allocator (the 8 Gbyte level on node 0 in the example above) does not cost too much, I think there is no use to add complexity to the allocator code. Thanks, Zoltan Menyhart P.S. I guess it is not an ia64-only issue. - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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