Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint

From: Michal Hocko
Date: Fri Dec 30 2016 - 12:30:56 EST

On Fri 30-12-16 17:37:42, Michal Hocko wrote:
> On Sat 31-12-16 01:04:56, Minchan Kim wrote:
> > > - nr_rotated pages which tells us that we are hitting referenced
> > > pages which are deactivated. If this is a large part of the
> > > reported nr_deactivated pages then the active list is too small
> >
> > It might be but not exactly. If your goal is to know LRU size, it can be
> > done in get_scan_count. I tend to agree LRU size is helpful for
> > performance analysis because decreased LRU size signals memory shortage
> > then performance drop.
> No, I am not really interested in the exact size but rather to allow to
> find whether we are aging the active list too early...

But thinking about that some more, maybe sticking with the nr_rotated
terminology is rather confusing and displaying the value as nr_referenced
would be more clear.
Michal Hocko