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SubjectRe: [PATCH 08/10] vmscan: Setup pagevec as late as possible in shrink_inactive_list()
On Fri, Apr 16, 2010 at 03:30:00PM +0900, KOSAKI Motohiro wrote:
> > shrink_inactive_list() sets up a pagevec to release unfreeable pages. It
> > uses significant amounts of stack doing this. This patch splits
> > shrink_inactive_list() to take the stack usage out of the main path so
> > that callers to writepage() do not contain an unused pagevec on the
> > stack.
> >
> > Signed-off-by: Mel Gorman <mel@csn.ul.ie>
> > ---
> > mm/vmscan.c | 93 +++++++++++++++++++++++++++++++++-------------------------
> > 1 files changed, 53 insertions(+), 40 deletions(-)
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index a232ad6..9bc1ede 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -1120,6 +1120,54 @@ static int too_many_isolated(struct zone *zone, int file,
> > }
> >
> > /*
> > + * TODO: Try merging with migrations version of putback_lru_pages
> > + */
>
> I also think this stuff need more cleanups. but this patch works and
> no downside. So, Let's merge this at first.

Agreed. I was keeping the first-pass straight-forward and didn't want to
do too much in one patch to ease review.

> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
>
>
> but please fix Dave's pointed one.
>

Done. Thanks Dave, I hadn't spotted noinline_for_stack but it's exactly
what was needed here. It's not obvious why I used noinline otherwise.

>
> > +static noinline void putback_lru_pages(struct zone *zone,
> > + struct zone_reclaim_stat *reclaim_stat,
> > + unsigned long nr_anon, unsigned long nr_file,
> > + struct list_head *page_list)
> > +{
> > + struct page *page;
> > + struct pagevec pvec;
> > +
> > + pagevec_init(&pvec, 1);
> > +
> > + /*
> > + * Put back any unfreeable pages.
> > + */
> > + spin_lock(&zone->lru_lock);
> > + while (!list_empty(page_list)) {
> > + int lru;
> > + page = lru_to_page(page_list);
> > + VM_BUG_ON(PageLRU(page));
> > + list_del(&page->lru);
> > + if (unlikely(!page_evictable(page, NULL))) {
> > + spin_unlock_irq(&zone->lru_lock);
> > + putback_lru_page(page);
> > + spin_lock_irq(&zone->lru_lock);
> > + continue;
> > + }
> > + SetPageLRU(page);
> > + lru = page_lru(page);
> > + add_page_to_lru_list(zone, page, lru);
> > + if (is_active_lru(lru)) {
> > + int file = is_file_lru(lru);
> > + reclaim_stat->recent_rotated[file]++;
> > + }
> > + if (!pagevec_add(&pvec, page)) {
> > + spin_unlock_irq(&zone->lru_lock);
> > + __pagevec_release(&pvec);
> > + spin_lock_irq(&zone->lru_lock);
> > + }
> > + }
> > + __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
> > + __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
> > +
> > + spin_unlock_irq(&zone->lru_lock);
> > + pagevec_release(&pvec);
> > +}
> > +
> > +/*
> > * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
> > * of reclaimed pages
> > */
> > @@ -1128,12 +1176,10 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> > int file)
> > {
> > LIST_HEAD(page_list);
> > - struct pagevec pvec;
> > unsigned long nr_scanned;
> > unsigned long nr_reclaimed = 0;
> > struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
> > int lumpy_reclaim = 0;
> > - struct page *page;
> > unsigned long nr_taken;
> > unsigned long nr_active;
> > unsigned int count[NR_LRU_LISTS] = { 0, };
> > @@ -1160,8 +1206,6 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> > else if (sc->order && sc->priority < DEF_PRIORITY - 2)
> > lumpy_reclaim = 1;
> >
> > - pagevec_init(&pvec, 1);
> > -
> > lru_add_drain();
> > spin_lock_irq(&zone->lru_lock);
> > nr_taken = sc->isolate_pages(nr_to_scan,
> > @@ -1177,8 +1221,10 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> > __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scanned);
> > }
> >
> > - if (nr_taken == 0)
> > - goto done;
> > + if (nr_taken == 0) {
> > + spin_unlock_irq(&zone->lru_lock);
> > + return 0;
> > + }
> >
> > nr_active = clear_active_flags(&page_list, count);
> > __count_vm_events(PGDEACTIVATE, nr_active);
> > @@ -1229,40 +1275,7 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> > __count_vm_events(KSWAPD_STEAL, nr_reclaimed);
> > __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
> >
> > - spin_lock(&zone->lru_lock);
> > - /*
> > - * Put back any unfreeable pages.
> > - */
> > - while (!list_empty(&page_list)) {
> > - int lru;
> > - page = lru_to_page(&page_list);
> > - VM_BUG_ON(PageLRU(page));
> > - list_del(&page->lru);
> > - if (unlikely(!page_evictable(page, NULL))) {
> > - spin_unlock_irq(&zone->lru_lock);
> > - putback_lru_page(page);
> > - spin_lock_irq(&zone->lru_lock);
> > - continue;
> > - }
> > - SetPageLRU(page);
> > - lru = page_lru(page);
> > - add_page_to_lru_list(zone, page, lru);
> > - if (is_active_lru(lru)) {
> > - int file = is_file_lru(lru);
> > - reclaim_stat->recent_rotated[file]++;
> > - }
> > - if (!pagevec_add(&pvec, page)) {
> > - spin_unlock_irq(&zone->lru_lock);
> > - __pagevec_release(&pvec);
> > - spin_lock_irq(&zone->lru_lock);
> > - }
> > - }
> > - __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
> > - __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
> > -
> > -done:
> > - spin_unlock_irq(&zone->lru_lock);
> > - pagevec_release(&pvec);
> > + putback_lru_pages(zone, reclaim_stat, nr_anon, nr_file, &page_list);
> > return nr_reclaimed;
> > }
> >
> > --
> > 1.6.5
> >
>
>
>

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab


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