On Wed 04-01-17 15:51:43, Vlastimil Babka wrote:
[...]
> > @@ -1266,11 +1270,13 @@ static unsigned long shrink_page_list(struct
> > list_head *page_list,
> > list_splice(&ret_pages, page_list);
> > count_vm_events(PGACTIVATE, pgactivate);
> >
> > - *ret_nr_dirty += nr_dirty;
> > - *ret_nr_congested += nr_congested;
> > - *ret_nr_unqueued_dirty += nr_unqueued_dirty;
> > - *ret_nr_writeback += nr_writeback;
> > - *ret_nr_immediate += nr_immediate;
> > + if (stat) {
> > + stat->nr_dirty = nr_dirty;
> > + stat->nr_congested = nr_congested;
> > + stat->nr_unqueued_dirty = nr_unqueued_dirty;
> > + stat->nr_writeback = nr_writeback;
> > + stat->nr_immediate = nr_immediate;
> > + }
>
> This change of '+=' to '=' raised my eybrows, but it seems both callers
> don't care so this is indeed no functional change and potentially faster.
Yes, I was quite surprised as well, maybe we had a code which relied on
the aggregated numbers in the past but I didn't bother to go over git
logs to check. There is no such user anymore...
--
Michal Hocko
SUSE Labs
