Messages in this thread | | | Subject | Re: [PATCH] Make CONFIG_MIGRATION available for s390 | From | Gerald Schaefer <> | Date | Mon, 07 Jul 2008 19:28:09 +0200 |
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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
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