Re: [PATCH 18/34] mm: rename NR_ANON_PAGES to NR_ANON_MAPPED

[Mel Gorman]

On Tue, Jul 12, 2016 at 10:58:01AM -0400, Johannes Weiner wrote:
> On Fri, Jul 08, 2016 at 10:34:54AM +0100, Mel Gorman wrote:
> > NR_FILE_PAGES  is the number of        file pages.
> > NR_FILE_MAPPED is the number of mapped file pages.
> > NR_ANON_PAGES  is the number of mapped anon pages.
> > 
> > This is unhelpful naming as it's easy to confuse NR_FILE_MAPPED and
> > NR_ANON_PAGES for mapped pages.  This patch renames NR_ANON_PAGES so we
> > have
> > 
> > NR_FILE_PAGES  is the number of        file pages.
> > NR_FILE_MAPPED is the number of mapped file pages.
> > NR_ANON_MAPPED is the number of mapped anon pages.
> 
> That looks wrong to me. The symmetry is between NR_FILE_PAGES and
> NR_ANON_PAGES. NR_FILE_MAPPED is merely elaborating on the mapped
> subset of NR_FILE_PAGES, something which isn't necessary for anon
> pages as they're always mapped.

How strongly do you feel about reverting it as later patches would cause
lots of conflicts.

Obviously I found the new names clearer but I was thinking a lot at the
time about mapped vs unmapped due to looking closely at both reclaim and
[f|m]advise functions at the time. I found it mildly irksome to switch
between the semantics of file/anon when looking at the vmstat updates.

-- 
Mel Gorman
SUSE Labs