From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx110.postini.com [74.125.245.110]) by kanga.kvack.org (Postfix) with SMTP id 57ED26B0034 for ; Fri, 2 Aug 2013 12:06:45 -0400 (EDT) From: Andrea Arcangeli Subject: [PATCH 5/9] mm: compaction: don't require high order pages below min wmark Date: Fri, 2 Aug 2013 18:06:32 +0200 Message-Id: <1375459596-30061-6-git-send-email-aarcange@redhat.com> In-Reply-To: <1375459596-30061-1-git-send-email-aarcange@redhat.com> References: <1375459596-30061-1-git-send-email-aarcange@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Johannes Weiner , Mel Gorman , Rik van Riel , Hugh Dickins , Richard Davies , Shaohua Li , Rafael Aquini , Andrew Morton , Hush Bensen 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 092b30d..4401983 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; for (o = 0; o < order; o++) { /* At the next order, this order's pages become unavailable */ free_pages -= z->free_area[o].nr_free << o; -- 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