From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932630AbbI3ORw (ORCPT ); Wed, 30 Sep 2015 10:17:52 -0400 Received: from mx2.suse.de ([195.135.220.15]:40966 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755003AbbI3ORr (ORCPT ); Wed, 30 Sep 2015 10:17:47 -0400 Subject: Re: [PATCH 10/10] mm, page_alloc: Only enforce watermarks for order-0 allocations To: Mel Gorman , Andrew Morton References: <1442832762-7247-1-git-send-email-mgorman@techsingularity.net> <20150921120317.GC3068@techsingularity.net> <20150929140507.82b5e02f300038e4bb5b2493@linux-foundation.org> <20150930084650.GM3068@techsingularity.net> Cc: Johannes Weiner , Rik van Riel , David Rientjes , Joonsoo Kim , Michal Hocko , Linux-MM , LKML From: Vlastimil Babka Message-ID: <560BEF08.60704@suse.cz> Date: Wed, 30 Sep 2015 16:17:44 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <20150930084650.GM3068@techsingularity.net> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/30/2015 10:46 AM, Mel Gorman wrote: > On Tue, Sep 29, 2015 at 02:05:07PM -0700, Andrew Morton wrote: > > The wizard of oz because because! > > This should fix it up better than clicking my shoes three times. > > ---8<--- > From: Mel Gorman > Subject: [PATCH] mm, page_alloc: only enforce watermarks for order-0 > allocations -fix > > This patch is updating comments for clarity and converts a bool to an > int. The code as-is is ok as the compiler is meant to cast it correctly > but it looks odd to people who know the value would be truncated and > lost for other types. > > This is a fix to the mmotm patch > mm-page_alloc-only-enforce-watermarks-for-order-0-allocations.patch > > Signed-off-by: Mel Gorman Ack (with nitpick below) > --- > mm/page_alloc.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 25731624d734..fedec98aafca 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2332,7 +2332,7 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order, > { > long min = mark; > int o; > - const bool alloc_harder = (alloc_flags & ALLOC_HARDER); > + const int alloc_harder = (alloc_flags & ALLOC_HARDER); How bout the !!(alloc_flags & ALLOC_HARDER) conversion to bool? Unless it forces to make the compiler some extra work... > > /* free_pages may go negative - that's OK */ > free_pages -= (1 << order) - 1; > @@ -2356,14 +2356,19 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order, > free_pages -= zone_page_state(z, NR_FREE_CMA_PAGES); > #endif > > + /* > + * Check watermarks for an order-0 allocation request. If these > + * are not met, then a high-order request also cannot go ahead > + * even if a suitable page happened to be free. > + */ > if (free_pages <= min + z->lowmem_reserve[classzone_idx]) > return false; > > - /* order-0 watermarks are ok */ > + /* If this is an order-0 request then the watermark is fine */ > if (!order) > return true; > > - /* Check at least one high-order page is free */ > + /* For a high-order request, check at least one suitable page is free */ > for (o = order; o < MAX_ORDER; o++) { > struct free_area *area = &z->free_area[o]; > int mt; >