From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755265AbdGKGui (ORCPT ); Tue, 11 Jul 2017 02:50:38 -0400 Received: from mx2.suse.de ([195.135.220.15]:60129 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753306AbdGKGuh (ORCPT ); Tue, 11 Jul 2017 02:50:37 -0400 Date: Tue, 11 Jul 2017 08:50:30 +0200 From: Michal Hocko To: Vlastimil Babka Cc: Anshuman Khandual , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mike.kravetz@oracle.com Subject: Re: [RFC] mm/mremap: Remove redundant checks inside vma_expandable() Message-ID: <20170711065030.GE24852@dhcp22.suse.cz> References: <20170710111059.30795-1-khandual@linux.vnet.ibm.com> <20170710134917.GB19645@dhcp22.suse.cz> <20170711060354.GA24852@dhcp22.suse.cz> <4c182da0-6c84-df67-b173-6960fac0544a@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4c182da0-6c84-df67-b173-6960fac0544a@suse.cz> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 11-07-17 08:26:40, Vlastimil Babka wrote: > On 07/11/2017 08:03 AM, Michal Hocko wrote: > > On Tue 11-07-17 09:58:42, Anshuman Khandual wrote: > >>> here. This is hardly something that would save many cycles in a > >>> relatively cold path. > >> > >> Though I have not done any detailed instruction level measurement, > >> there is a reduction in real and system amount of time to execute > >> the test with and without the patch. > >> > >> Without the patch > >> > >> real 0m2.100s > >> user 0m0.162s > >> sys 0m1.937s > >> > >> With this patch > >> > >> real 0m0.928s > >> user 0m0.161s > >> sys 0m0.756s > > > > Are you telling me that two if conditions cause more than a second > > difference? That sounds suspicious. > > It's removing also a call to get_unmapped_area(), AFAICS. That means a > vma search? Ohh, right. I have somehow missed that. Is this removal intentional? The changelog is silent about it. -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 1C2AD6B04C4 for ; Tue, 11 Jul 2017 02:50:37 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id z45so29316473wrb.13 for ; Mon, 10 Jul 2017 23:50:37 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id l11si10511998wrl.217.2017.07.10.23.50.36 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 10 Jul 2017 23:50:36 -0700 (PDT) Date: Tue, 11 Jul 2017 08:50:30 +0200 From: Michal Hocko Subject: Re: [RFC] mm/mremap: Remove redundant checks inside vma_expandable() Message-ID: <20170711065030.GE24852@dhcp22.suse.cz> References: <20170710111059.30795-1-khandual@linux.vnet.ibm.com> <20170710134917.GB19645@dhcp22.suse.cz> <20170711060354.GA24852@dhcp22.suse.cz> <4c182da0-6c84-df67-b173-6960fac0544a@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4c182da0-6c84-df67-b173-6960fac0544a@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Anshuman Khandual , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mike.kravetz@oracle.com On Tue 11-07-17 08:26:40, Vlastimil Babka wrote: > On 07/11/2017 08:03 AM, Michal Hocko wrote: > > On Tue 11-07-17 09:58:42, Anshuman Khandual wrote: > >>> here. This is hardly something that would save many cycles in a > >>> relatively cold path. > >> > >> Though I have not done any detailed instruction level measurement, > >> there is a reduction in real and system amount of time to execute > >> the test with and without the patch. > >> > >> Without the patch > >> > >> real 0m2.100s > >> user 0m0.162s > >> sys 0m1.937s > >> > >> With this patch > >> > >> real 0m0.928s > >> user 0m0.161s > >> sys 0m0.756s > > > > Are you telling me that two if conditions cause more than a second > > difference? That sounds suspicious. > > It's removing also a call to get_unmapped_area(), AFAICS. That means a > vma search? Ohh, right. I have somehow missed that. Is this removal intentional? The changelog is silent about it. -- 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