On Thu, 19 Jun 2014 08:04:32 +0800 Chen Yucong <slaoub@xxxxxxxxx> wrote:
> On Wed, 2014-06-18 at 15:27 -0700, Andrew Morton wrote:
> > On Tue, 17 Jun 2014 12:55:02 +0800 Chen Yucong <slaoub@xxxxxxxxx> wrote:
> >
> > > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > > index a8ffe4e..2c35e34 100644
> > > --- a/mm/vmscan.c
> > > +++ b/mm/vmscan.c
> > > @@ -2087,8 +2086,8 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
> > > blk_start_plug(&plug);
> > > while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
> > > nr[LRU_INACTIVE_FILE]) {
> > > - unsigned long nr_anon, nr_file, percentage;
> > > - unsigned long nr_scanned;
> > > + unsigned long nr_anon, nr_file, file_percent, anon_percent;
> > > + unsigned long nr_to_scan, nr_scanned, percentage;
> > >
> > > for_each_evictable_lru(lru) {
> > > if (nr[lru]) {
> >
> > The increased stack use is a slight concern - we can be very deep here.
> > I suspect the "percent" locals are more for convenience/clarity, and
> > they could be eliminated (in a separate patch) at some cost of clarity?
> >
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index a8ffe4e..2c35e34 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2057,8 +2057,7 @@ out:
> static void shrink_lruvec(struct lruvec *lruvec, struct scan_control
> *sc)
> {
> unsigned long nr[NR_LRU_LISTS];
> - unsigned long targets[NR_LRU_LISTS];
> - unsigned long nr_to_scan;
> + unsigned long file_target, anon_target;
>
> >From the above snippet, we can know that the "percent" locals come from
> targets[NR_LRU_LISTS]. So this fix does not increase the stack.
OK. But I expect the stack use could be decreased by using more
complex expressions.
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