Re: ia64 ORDERROUNDDOWN issue

From: Zoltan Menyhart <Zoltan.Menyhart_at_bull.net>
Date: 2006-11-30 21:47:09
>> 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 inside
>> the 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@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Received on Thu Nov 30 21:47:32 2006

This archive was generated by hypermail 2.1.8 : 2006-11-30 21:47:52 EST