Re: [RFC] Track mlock()ed pages

Christoph Lameter
2007-01-26T15:44:49Z

On Fri, 26 Jan 2007, Andrew Morton wrote:

> > > > Track mlocked pages via a ZVC
>
> Why?

Large amounts of mlocked pages may be a problem for

1. Reclaim behavior.

2. Defragmentation

> You could perhaps go for a walk across all the other vmas which presently
> map this page. If any of them have VM_LOCKED, don't increment the counter.
> Similar on removal: only decrement the counter when the final mlocked VMA
> is dropping the pte.

For that we would need an additional refcount for vmlocked maps in the
page struct. Looks too expensive.