From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id C53D56B004D for ; Tue, 21 Apr 2009 03:45:42 -0400 (EDT) Subject: Re: [PATCH 12/25] Remove a branch by assuming __GFP_HIGH == ALLOC_HIGH From: Pekka Enberg In-Reply-To: <1240266011-11140-13-git-send-email-mel@csn.ul.ie> References: <1240266011-11140-1-git-send-email-mel@csn.ul.ie> <1240266011-11140-13-git-send-email-mel@csn.ul.ie> Date: Tue, 21 Apr 2009 10:46:22 +0300 Message-Id: <1240299982.771.48.camel@penberg-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: Linux Memory Management List , KOSAKI Motohiro , Christoph Lameter , Nick Piggin , Linux Kernel Mailing List , Lin Ming , Zhang Yanmin , Peter Zijlstra , Andrew Morton List-ID: On Mon, 2009-04-20 at 23:19 +0100, Mel Gorman wrote: > Allocations that specify __GFP_HIGH get the ALLOC_HIGH flag. If these > flags are equal to each other, we can eliminate a branch. > > [akpm@linux-foundation.org: Suggested the hack] Yikes! > Signed-off-by: Mel Gorman > --- > mm/page_alloc.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 51e1ded..b13fc29 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1639,8 +1639,8 @@ gfp_to_alloc_flags(gfp_t gfp_mask) > * policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will > * set both ALLOC_HARDER (!wait) and ALLOC_HIGH (__GFP_HIGH). > */ > - if (gfp_mask & __GFP_HIGH) > - alloc_flags |= ALLOC_HIGH; > + VM_BUG_ON(__GFP_HIGH != ALLOC_HIGH); > + alloc_flags |= (gfp_mask & __GFP_HIGH); Shouldn't you then also change ALLOC_HIGH to use __GFP_HIGH or at least add a comment somewhere? > > if (!wait) { > alloc_flags |= ALLOC_HARDER; -- 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