| Subject | Re: [PATCH 18/25] Do not disable interrupts in free_page_mlock() | From | Pekka Enberg <> | Date | Tue, 21 Apr 2009 10:55:07 +0300 |
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On Mon, 2009-04-20 at 23:20 +0100, Mel Gorman wrote: > 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. > > Signed-off-by: Mel Gorman <mel@csn.ul.ie> > Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
> --- > 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); > - }
Maybe add a VM_BUG_ON(!PageMlocked(page))?
> + __ClearPageMlocked(page); > + __dec_zone_page_state(page, NR_MLOCK); > + __count_vm_event(UNEVICTABLE_MLOCKFREED); > } > > #else /* CONFIG_HAVE_MLOCKED_PAGE_BIT */
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