[PATCH v3] mm: introduce reference pages

[Matthew Wilcox]

On Mon, Aug 17, 2020 at 07:31:39PM -0700, John Hubbard wrote:
> >            Real time (s)    Max RSS (KiB)
> > anon        2.237081         107088
> > memset      2.252241         112180
> > refpage     2.243786         107128
> > 
> > We can see that RSS for refpage is almost the same as anon, and real
> > time overhead is 44% that of memset.
> > 
> 
> Are some of the numbers stale, maybe? Try as I might, I cannot combine
> anything above to come up with 44%. :)

You're not trying hard enough ;-)

(2.252241 - 2.237081) / 2.237081 = .00677668801442594166
(2.243786 - 2.237081) / 2.237081 = .00299720930981041812
.00299720930981041812 / .00677668801442594166 = .44228232189973614648

tadaa!

As I said last time this was posted, I'm just not excited by this.  We go
from having a 0.68% time overhead down to an 0.30% overhead, which just
doesn't move the needle for me.  Maybe there's a better benchmark than
this to show benefits from this patchset.