From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754103AbdGKJpv (ORCPT ); Tue, 11 Jul 2017 05:45:51 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:37513 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751064AbdGKJpt (ORCPT ); Tue, 11 Jul 2017 05:45:49 -0400 Subject: Re: [RFC] mm/mremap: Remove redundant checks inside vma_expandable() To: Vlastimil Babka , Michal Hocko , Anshuman Khandual 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> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mike.kravetz@oracle.com From: Anshuman Khandual Date: Tue, 11 Jul 2017 15:14:27 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <4c182da0-6c84-df67-b173-6960fac0544a@suse.cz> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable x-cbid: 17071109-0012-0000-0000-00000255878A X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17071109-0013-0000-0000-0000076EECB2 Message-Id: <210533b7-3b29-b6bd-24db-03e0c756a882@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-11_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1707110151 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/11/2017 11:56 AM, 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? I believe removing this function is responsible for the increase in speed of the test execution.