On Wed, Jul 17, 2013 at 04:13:04AM -0400, Hush Bensen wrote: > On 07/16/2013 09:41 AM, Andrea Arcangeli wrote: > > The min wmark should be satisfied with just 1 hugepage. And the other > > wmarks should be adjusted accordingly. We need to succeed the low > > wmark check if there's some significant amount of 0 order pages, but > > we don't need plenty of high order pages because the PF_MEMALLOC paths > > don't require those. Creating a ton of high order pages that cannot be > > allocated by the high order allocation paths (no PF_MEMALLOC) is quite > > wasteful because they can be splitted in lower order pages before > > anybody has a chance to allocate them. > > > > Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> > > --- > > mm/page_alloc.c | 17 +++++++++++++++++ > > 1 file changed, 17 insertions(+) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index db8fb66..d94503d 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -1643,6 +1643,23 @@ static bool __zone_watermark_ok(struct zone *z, int order, unsigned long mark, > > > > if (free_pages - free_cma <= min + lowmem_reserve) > > return false; > > + if (!order) > > + return true; > > + > > + /* > > + * Don't require any high order page under the min > > + * wmark. Invoking compaction to create lots of high order > > + * pages below the min wmark is wasteful because those > > + * hugepages cannot be allocated without PF_MEMALLOC and the > > + * PF_MEMALLOC paths must not depend on high order allocations > > + * to succeed. > > + */ > > + min = mark - z->watermark[WMARK_MIN]; > > + WARN_ON(min < 0); > > + if (alloc_flags & ALLOC_HIGH) > > + min -= min / 2; > > + if (alloc_flags & ALLOC_HARDER) > > + min -= min / 4; > > __zone_watermark_ok has these operations for mark, why do it again? min changed, so I repeat the operation on the new min. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>