Re: [PATCH 3/3] Provide control over unmapped pages

Christoph Lameter
2010-12-01T15:01:36Z

On Tue, 30 Nov 2010, Andrew Morton wrote:

> > +#define UNMAPPED_PAGE_RATIO 16
>
> Well. Giving 16 a name didn't really clarify anything. Attentive
> readers will want to know what this does, why 16 was chosen and what
> the effects of changing it will be.

The meaning is analoguous to the other zone reclaim ratio. But yes it
should be justified and defined.

> > Reviewed-by: Christoph Lameter <cl@linux.com>
>
> So you're OK with shoving all this flotsam into 100,000,000 cellphones?
> This was a pretty outrageous patchset!

This is a feature that has been requested over and over for years. Using
/proc/vm/drop_caches for fixing situations where one simply has too many
page cache pages is not so much fun in the long run.