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

KAMEZAWA Hiroyuki
2007-02-07T10:49:57Z

On Wed, 7 Feb 2007 11:41:25 +0100
Andi Kleen <ak@suse.de> wrote:

> On Wednesday 07 February 2007 11:37, KAMEZAWA Hiroyuki wrote:
> > On Wed, 7 Feb 2007 11:19:02 +0100
> > Andi Kleen <ak@suse.de> wrote:
> > > You can also alias node numbers to solve this: just point multiple node numbers
> > > to the same pgdat. For a memory less node this would be a nearby one.
> > >
> > Hmm, interesting...the 'alias' means follwing ?
>
> Yes.
>
> > NODE_DATA(A) = pgdat_for_A
> > NODE_DATA(B) = pgdat_for_A // B is memory-less.
> > - NODE_DATA(B) is valid but B is not online.
>
> Well it is online because A is. For all practical purposes
> it is A, just under a different name.
>
> > ==
> > looks complicated..and we have to care /sys/devices/system/node handling.
>
> x86-64 used to do that when it still only did 1:1 cpu<->memory mappings.
> I don't remember any problems with it.
>

How for_each_online_node(nid) works ? it can handle alias-nid ?

==
for_each_online_node(nid) {
pgdat = NODE_DATA(nid);
==
This code never accesses pgdat_for_A twice ?

Thanks,
-Kame