[ofa-general] Re: [patch 0/6] MMU Notifiers V6

[Christoph Lameter]

On Fri, 8 Feb 2008, Andrew Morton wrote:

> What about ib_umem_get()?

Ok. It pins using an elevated refcount. Same as XPmem right now. With that 
we effectively pin a page (page migration will fail) but we will 
continually be reclaiming the page and may repeatedly try to move it. We 
have issues with XPmem causing too many pages to be pinned and thus the 
OOM getting into weird behavior modes (OOM or stop lru scanning due to 
all_reclaimable set).

An elevated refcount will also not be noticed by any of the schemes under 
consideration to improve LRU scanning performance.