On Mon, 20 Jul 2020 13:42:45 +0800 Alex Shi <[email protected]> wrote:
> > For couple of vmstat account funcs, the caller usually doesn't check the > delta value, if delta == 0, irq or atomic operator is a waste. That's > better to be skipped, also add unlikey() since !delta is less happened. > > ... > > --- a/mm/vmstat.c > +++ b/mm/vmstat.c > @@ -321,6 +321,9 @@ void __mod_zone_page_state(struct zone *zone, enum > zone_stat_item item, > long x; > long t; > > + if (unlikely(!delta)) > + return; > + Do we know that delta==0 is frequent enough to make the change a net benefit?
