From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx118.postini.com [74.125.245.118]) by kanga.kvack.org (Postfix) with SMTP id 2368C6B0032 for ; Fri, 2 Aug 2013 12:27:26 -0400 (EDT) Date: Fri, 2 Aug 2013 18:27:22 +0200 From: Michal Hocko Subject: Re: [PATCH 1/4] mm, page_alloc: add likely macro to help compiler optimization Message-ID: <20130802162722.GA29220@dhcp22.suse.cz> References: <1375409279-16919-1-git-send-email-iamjoonsoo.kim@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1375409279-16919-1-git-send-email-iamjoonsoo.kim@lge.com> Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim , Minchan Kim , Johannes Weiner , Mel Gorman , Rik van Riel On Fri 02-08-13 11:07:56, Joonsoo Kim wrote: > We rarely allocate a page with ALLOC_NO_WATERMARKS and it is used > in slow path. For making fast path more faster, add likely macro to > help compiler optimization. The code is different in mmotm tree (see mm: page_alloc: rearrange watermark checking in get_page_from_freelist) Besides that, make sure you provide numbers which prove your claims about performance optimizations. > Signed-off-by: Joonsoo Kim > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index b100255..86ad44b 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1901,7 +1901,7 @@ zonelist_scan: > goto this_zone_full; > > BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK); > - if (!(alloc_flags & ALLOC_NO_WATERMARKS)) { > + if (likely(!(alloc_flags & ALLOC_NO_WATERMARKS))) { > unsigned long mark; > int ret; > > -- > 1.7.9.5 > > -- > 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 -- Michal Hocko SUSE Labs -- 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