Re: [2.6.20][PATCH] fix mempolicy error check on a system withmemory-less-node

[KAMEZAWA Hiroyuki]

On 07 Feb 2007 11:20:06 +0100
Andi Kleen <ak@xxxxxxx> wrote:

> KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> writes:
> 
> > current mempolicy just checks whether a node is online or not.
> > If there is memory-less-node, mempolicy's target node can be
> > invalid.
> > This patch adds a check whether a node has memory or not.
> 
> IMHO there shouldn't be any memory less nodes. The architecture code
> should not create them. The CPU should be assigned to a nearby node instead.
> At least x86-64 ensures that.
> 
AFAIK, ia64 creates nodes just depends on SRAT's possible resource information.
Then, ia64 can create cpu-memory-less-node(node with no available resource.).
(*)I don't like this.

If we don't allow memory-less-node, we may have to add several codes for cpu-hot-add.
cpus should be moved to nearby node at hotadd .
And node-hot-add have to care that cpus mustn't be added before memory, cpu-driven 
node-hot-add will never occur. (ACPI's 'container' device spec can't guaranntee this.)

-Kame



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