On Wed, Sep 08, 2010 at 08:50:44PM +0800, Mel Gorman wrote:
> On Wed, Sep 08, 2010 at 07:37:34PM +0800, Wu Fengguang wrote:
> > On Mon, Sep 06, 2010 at 06:47:31PM +0800, Mel Gorman wrote:
> > > From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> > >
> > > isolate_lru_pages() does not just isolate LRU tail pages, but also isolate
> > > neighbour pages of the eviction page. The neighbour search does not stop even
> > > if neighbours cannot be isolated which is excessive as the lumpy reclaim will
> > > no longer result in a successful higher order allocation. This patch stops
> > > the PFN neighbour pages if an isolation fails and moves on to the next block.
> > >
> > > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> > > Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
> > > ---
> > > mm/vmscan.c | 24 ++++++++++++++++--------
> > > 1 files changed, 16 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > > index 64f9ca5..ff52b46 100644
> > > --- a/mm/vmscan.c
> > > +++ b/mm/vmscan.c
> > > @@ -1047,14 +1047,18 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
> > > continue;
> > >
> > > /* Avoid holes within the zone. */
> > > - if (unlikely(!pfn_valid_within(pfn)))
> > > + if (unlikely(!pfn_valid_within(pfn))) {
> > > + nr_lumpy_failed++;
> > > break;
> > > + }
> > >
> > > cursor_page = pfn_to_page(pfn);
> > >
> > > /* Check that we have not crossed a zone boundary. */
> > > - if (unlikely(page_zone_id(cursor_page) != zone_id))
> > > - continue;
> > > + if (unlikely(page_zone_id(cursor_page) != zone_id)) {
> > > + nr_lumpy_failed++;
> > > + break;
> > > + }
> > >
> > > /*
> > > * If we don't have enough swap space, reclaiming of
> > > @@ -1062,8 +1066,10 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
> > > * pointless.
> > > */
> > > if (nr_swap_pages <= 0 && PageAnon(cursor_page) &&
> > > - !PageSwapCache(cursor_page))
> > > - continue;
> > > + !PageSwapCache(cursor_page)) {
> > > + nr_lumpy_failed++;
> > > + break;
> > > + }
> > >
> > > if (__isolate_lru_page(cursor_page, mode, file) == 0) {
> > > list_move(&cursor_page->lru, dst);
> > > @@ -1074,9 +1080,11 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
> > > nr_lumpy_dirty++;
> > > scan++;
> > > } else {
> > > - if (mode == ISOLATE_BOTH &&
> > > - page_count(cursor_page))
> > > - nr_lumpy_failed++;
> > > + /* the page is freed already. */
> > > + if (!page_count(cursor_page))
> > > + continue;
> > > + nr_lumpy_failed++;
> > > + break;
> > > }
> > > }
> >
> > The many nr_lumpy_failed++ can be moved here:
> >
> > if (pfn < end_pfn)
> > nr_lumpy_failed++;
> >
>
> Because the break stops the loop iterating, is there an advantage to
> making it a pfn check instead? I might be misunderstanding your
> suggestion.
The complete view in my mind is
for (; pfn < end_pfn; pfn++) {
if (failed 1)
break;
if (failed 2)
break;
if (failed 3)
break;
}
if (pfn < end_pfn)
nr_lumpy_failed++;
Sure it just reduces several lines of code :)
Thanks,
Fengguang
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