lkml.org 
[lkml]   [2008]   [Jul]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] Make CONFIG_MIGRATION available for s390
From
Date
On Mon, 2008-07-07 at 10:09 -0500, Christoph Lameter wrote:
> This will extend the number of pages that are migratable and lead to strange
> semantics in the NUMA case. There suddenly vma_is migratable will forbid hotplug
> to migrate certain pages.
>
> I think we need two functions:
>
> vma_migratable() General migratability
>
> vma_policy_migratable() Migratable under NUMA policies.

Nothing will change here for the NUMA case, this is all about making it
compile w/o NUMA and with MIGRATION. What new strange semantics do you mean?
BTW, the latest patch in this thread will not touch vma_migratable() anymore,
I haven't read your mail before, sorry.

> That wont work since the migrate function takes a nodemask! The point of
> the function is to move memory from node to node which is something that you
> *cannot* do in a non NUMA configuration. So leave this chunk out.

Right, but I noticed that this function definition was needed to make it
compile with MIGRATION and w/o NUMA, although it would never be called in
non-NUMA config.
A better solution would probably be to put migrate_vmas(), the only caller
of vm_ops->migrate(), inside '#ifdef CONFIG_NUMA', because it will only be
called from NUMA-only mm/mempolicy.c. Does that sound reasonable?

> Hmmm... Okay. I tried to make MIGRATION as independent of CONFIG_NUMA as possible so hopefully this will work.

Umm, it doesn't compile with MIGRATION and w/o NUMA, which was the reason
for this patch, because of the policy_zone reference in vma_migratable()
and the missing vm_ops->migrate() function.

Thanks,
Gerald



\
 
 \ /
  Last update: 2008-07-07 19:31    [from the cache]
©2003-2011 Jasper Spaans