Re: [PATCH 2/6] mempolicy: Kill all mempolicy sharing

[Andi Kleen]

On Wed, May 30, 2012 at 02:41:22PM -0500, Christoph Lameter wrote:
> On Wed, 30 May 2012, kosaki.motohiro@xxxxxxxxx wrote:
> 
> > refcount will be decreased even though was not increased whenever alloc_page_vma()
> > is called. As you know, mere mbind(MPOL_MF_MOVE) calls alloc_page_vma().
> 
> Most of these issues are about memory migration and shared memory. If we
> exempt shared memory from memory migration (after all that shared memory
> has its own distinct memory policies already!) then a lot of these issues
> wont arise.

Soft memory offlining needs migration. It's fairly important that this
works: on the database systems most memory is in shared memory and they
have a lot of memory, so predictive failure analysis and soft offlining
helps a lot.

Classic migration is probably not too important here, but they pretty
much rely on the same low level mechanism.

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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