Re: [PATCH v2] mm: exclude isolated non-lru pages from NR_ISOLATED_ANON or NR_ISOLATED_FILE.

From: Minchan Kim
Date: Fri Oct 14 2016 - 10:45:14 EST

On Fri, Oct 14, 2016 at 03:53:34PM +0200, Michal Hocko wrote:
> On Fri 14-10-16 22:46:04, Minchan Kim wrote:
> [...]
> > > > > Why don't you simply mimic what shrink_inactive_list does? Aka count the
> > > > > number of isolated pages and then account them when appropriate?
> > > > >
> > > > I think i am correcting clearly wrong part. So, there is no need to
> > > > describe it too detailed. It's a misunderstanding, and i will add
> > > > more comments as you suggest.
> > >
> > > OK, so could you explain why you prefer to relyon __PageMovable rather
> > > than do a trivial counting during the isolation?
> >
> > I don't get it. Could you elaborate it a bit more?
> It is really simple. You can count the number of file and anonymous
> pages while they are isolated and then account them to NR_ISOLATED_*
> later. Basically the same thing we do during the reclaim. We absolutely
> do not have to rely on __PageMovable and make this code more complex
> than necessary.

I don't understand your point.
isolate_migratepages_block can isolate any movable pages, for instance,
anon, file and non-lru and they are isolated into cc->migratepges.
Then, acct_isolated accounts them to NR_ISOLATED_*.
Isn't it same with the one you suggested?
The problem is we should identify which pages is non-lru movable first.
If it's not non-lru, it means the page is either anon or file so we
can account them.
That's exactly waht Ming Ling did.

Sorry if I didn't get your point. Maybe, it would be better to give
pseudo code out of your mind for better understanding rather than
several ping-ping with vague words.