Messages in this thread | | | Subject | Re: [PATCH 18/25] Do not disable interrupts in free_page_mlock() | From | Lee Schermerhorn <> | Date | Wed, 22 Apr 2009 10:43:00 -0400 |
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On Wed, 2009-04-22 at 09:13 +0900, KOSAKI Motohiro wrote: > (cc to Lee) > > > free_page_mlock() tests and clears PG_mlocked using locked versions of the > > bit operations. If set, it disables interrupts to update counters and this > > happens on every page free even though interrupts are disabled very shortly > > afterwards a second time. This is wasteful. > > > > This patch splits what free_page_mlock() does. The bit check is still > > made. However, the update of counters is delayed until the interrupts are > > disabled and the non-lock version for clearing the bit is used. One potential > > weirdness with this split is that the counters do not get updated if the > > bad_page() check is triggered but a system showing bad pages is getting > > screwed already. > > Looks good. thanks good improvement. > I hope Lee also ack this. > > Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> > > > -kosaki >
Yes, this looks OK. If we're racing on a page that is being freed or, as Mel notes, some other condition triggers bad_page(), we got bigger problems than inaccurate statistics...
Acked-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
> > > > > Signed-off-by: Mel Gorman <mel@csn.ul.ie> > > Reviewed-by: Christoph Lameter <cl@linux-foundation.org> > > --- > > mm/internal.h | 11 +++-------- > > mm/page_alloc.c | 8 +++++++- > > 2 files changed, 10 insertions(+), 9 deletions(-) > > > > diff --git a/mm/internal.h b/mm/internal.h > > index 987bb03..58ec1bc 100644 > > --- a/mm/internal.h > > +++ b/mm/internal.h > > @@ -157,14 +157,9 @@ static inline void mlock_migrate_page(struct page *newpage, struct page *page) > > */ > > static inline void free_page_mlock(struct page *page) > > { > > - if (unlikely(TestClearPageMlocked(page))) { > > - unsigned long flags; > > - > > - local_irq_save(flags); > > - __dec_zone_page_state(page, NR_MLOCK); > > - __count_vm_event(UNEVICTABLE_MLOCKFREED); > > - local_irq_restore(flags); > > - } > > + __ClearPageMlocked(page); > > + __dec_zone_page_state(page, NR_MLOCK); > > + __count_vm_event(UNEVICTABLE_MLOCKFREED); > > } > > > > #else /* CONFIG_HAVE_MLOCKED_PAGE_BIT */ > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index a1ca038..bf4b8d9 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -499,7 +499,6 @@ static inline void __free_one_page(struct page *page, > > > > static inline int free_pages_check(struct page *page) > > { > > - free_page_mlock(page); > > if (unlikely(page_mapcount(page) | > > (page->mapping != NULL) | > > (page_count(page) != 0) | > > @@ -556,6 +555,7 @@ static void __free_pages_ok(struct page *page, unsigned int order) > > unsigned long flags; > > int i; > > int bad = 0; > > + int clearMlocked = PageMlocked(page); > > > > for (i = 0 ; i < (1 << order) ; ++i) > > bad += free_pages_check(page + i); > > @@ -571,6 +571,8 @@ static void __free_pages_ok(struct page *page, unsigned int order) > > kernel_map_pages(page, 1 << order, 0); > > > > local_irq_save(flags); > > + if (unlikely(clearMlocked)) > > + free_page_mlock(page); > > __count_vm_events(PGFREE, 1 << order); > > free_one_page(page_zone(page), page, order, > > get_pageblock_migratetype(page)); > > @@ -1018,6 +1020,7 @@ static void free_hot_cold_page(struct page *page, int cold) > > struct zone *zone = page_zone(page); > > struct per_cpu_pages *pcp; > > unsigned long flags; > > + int clearMlocked = PageMlocked(page); > > > > if (PageAnon(page)) > > page->mapping = NULL; > > @@ -1033,7 +1036,10 @@ static void free_hot_cold_page(struct page *page, int cold) > > > > pcp = &zone_pcp(zone, get_cpu())->pcp; > > local_irq_save(flags); > > + if (unlikely(clearMlocked)) > > + free_page_mlock(page); > > __count_vm_event(PGFREE); > > + > > if (cold) > > list_add_tail(&page->lru, &pcp->list); > > else > > -- > > 1.5.6.5 > > > > >
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