From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753077AbcFOJkn (ORCPT ); Wed, 15 Jun 2016 05:40:43 -0400 Received: from mail-yw0-f194.google.com ([209.85.161.194]:35044 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751406AbcFOJkm (ORCPT ); Wed, 15 Jun 2016 05:40:42 -0400 MIME-Version: 1.0 In-Reply-To: <1465983258-3726-1-git-send-email-opensource.ganesh@gmail.com> References: <1465983258-3726-1-git-send-email-opensource.ganesh@gmail.com> From: Balbir Singh Date: Wed, 15 Jun 2016 19:40:40 +1000 Message-ID: Subject: Re: [PATCH v2] mm/page_alloc: remove unnecessary order check in __alloc_pages_direct_compact To: Ganesh Mahendran Cc: linux-mm , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , Vlastimil Babka , Joonsoo Kim , mhocko@suse.com, mina86@mina86.com, Minchan Kim , Anshuman Khandual Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 15, 2016 at 7:34 PM, Ganesh Mahendran wrote: > In the callee try_to_compact_pages(), the (order == 0) is checked, > so remove check in __alloc_pages_direct_compact. > > Signed-off-by: Ganesh Mahendran > --- > v2: > remove the check in __alloc_pages_direct_compact - Anshuman Khandual > --- > mm/page_alloc.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index b9ea618..2f5a82a 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3173,9 +3173,6 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, > struct page *page; > int contended_compaction; > > - if (!order) > - return NULL; > - > current->flags |= PF_MEMALLOC; > *compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac, > mode, &contended_compaction); What is the benefit of this. Is an if check more expensive than calling the function and returning from it? I don't feel strongly about such changes, but its good to audit the overall code for reading and performance. Balbir Singh