From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx155.postini.com [74.125.245.155]) by kanga.kvack.org (Postfix) with SMTP id 24E9E6B0032 for ; Wed, 17 Jul 2013 13:16:03 -0400 (EDT) Date: Wed, 17 Jul 2013 19:15:53 +0200 From: Andrea Arcangeli Subject: Re: [PATCH 05/10] mm: compaction: don't require high order pages below min wmark Message-ID: <20130717171553.GA6552@redhat.com> References: <1373982114-19774-1-git-send-email-aarcange@redhat.com> <1373982114-19774-6-git-send-email-aarcange@redhat.com> <51E65210.6040103@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51E65210.6040103@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Hush Bensen Cc: linux-mm@kvack.org, Mel Gorman , Rik van Riel , Hugh Dickins , Richard Davies , Shaohua Li , Rafael Aquini 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 > > --- > > 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@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org