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 290606B04BE for ; Tue, 11 Jul 2017 02:26:42 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id z1so29236124wrz.10 for ; Mon, 10 Jul 2017 23:26:42 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id d9si9889610wrc.290.2017.07.10.23.26.40 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 10 Jul 2017 23:26:41 -0700 (PDT) Subject: Re: [RFC] mm/mremap: Remove redundant checks inside vma_expandable() References: <20170710111059.30795-1-khandual@linux.vnet.ibm.com> <20170710134917.GB19645@dhcp22.suse.cz> <20170711060354.GA24852@dhcp22.suse.cz> From: Vlastimil Babka Message-ID: <4c182da0-6c84-df67-b173-6960fac0544a@suse.cz> Date: Tue, 11 Jul 2017 08:26:40 +0200 MIME-Version: 1.0 In-Reply-To: <20170711060354.GA24852@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Anshuman Khandual Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mike.kravetz@oracle.com 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? -- 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