Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932720AbdGJRP6 (ORCPT ); Mon, 10 Jul 2017 13:15:58 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:43285 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932067AbdGJRPy (ORCPT ); Mon, 10 Jul 2017 13:15:54 -0400 Date: Mon, 10 Jul 2017 10:15:36 -0700 From: Ram Pai To: Anshuman Khandual Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, dave.hansen@intel.com, hbabu@us.ibm.com, arnd@arndb.de, akpm@linux-foundation.org, corbet@lwn.net, mingo@redhat.com Subject: Re: [RFC v5 00/38] powerpc: Memory Protection Keys Reply-To: Ram Pai References: <1499289735-14220-1-git-send-email-linuxram@us.ibm.com> <20170710060544.GF5713@ram.oc3035372033.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170710060544.GF5713@ram.oc3035372033.ibm.com> User-Agent: Mutt/1.5.20 (2009-12-10) X-TM-AS-GCONF: 00 x-cbid: 17071017-8235-0000-0000-00000BE5B967 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007344; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000214; SDB=6.00885625; UDB=6.00441993; IPR=6.00665774; BA=6.00005464; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00016160; XFM=3.00000015; UTC=2017-07-10 17:15:52 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17071017-8236-0000-0000-00003CAE7F5A Message-Id: <20170710171536.GA5716@ram.oc3035372033.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-10_07:,, 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-1707100303 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 984 Lines: 24 On Sun, Jul 09, 2017 at 11:05:44PM -0700, Ram Pai wrote: > On Mon, Jul 10, 2017 at 11:13:23AM +0530, Anshuman Khandual wrote: > > On 07/06/2017 02:51 AM, Ram Pai wrote: ..... > > > do you have data points to show the difference in > > performance between this version and the last one where > > we skipped the bits from PTE and directly programmed the > > HPTE entries looking into VMA bits. > > No. I dont. I am hoping you can help me out with this. Anshuman, The last version where we skipped the PTE bits is guaranteed to be bad/horrible. For one it has a bug, since it accesses the vma without a lock. And even if we did take a lock, it will slow down the page-hash path un-acceptably. So there is no point measuring the performance of that design. I think the number we want to measure is -- the performance with the current design and comparing that to the performance without memkey feature. We want to find if there is any degradation by adding this feature. RP