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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 6 Sep 2018 08:45:08 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w867j7eO36110454 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 6 Sep 2018 07:45:07 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8C63311C05C; Thu, 6 Sep 2018 10:44:59 +0100 (BST) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4F9F611C054; Thu, 6 Sep 2018 10:44:58 +0100 (BST) Received: from [9.101.4.33] (unknown [9.101.4.33]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 6 Sep 2018 10:44:58 +0100 (BST) Subject: Re: Plumbers 2018 - Performance and Scalability Microconference To: Thomas Gleixner Cc: Christopher Lameter , Daniel Jordan , linux-kernel@vger.kernel.org, "linux-mm@kvack.org" , Aaron Lu , alex.kogan@oracle.com, akpm@linux-foundation.org, boqun.feng@gmail.com, brouer@redhat.com, dave@stgolabs.net, dave.dice@oracle.com, Dhaval Giani , ktkhai@virtuozzo.com, Pavel.Tatashin@microsoft.com, paulmck@linux.vnet.ibm.com, shady.issa@oracle.com, tariqt@mellanox.com, tim.c.chen@intel.com, vbabka@suse.cz, longman@redhat.com, yang.shi@linux.alibaba.com, shy828301@gmail.com, Huang Ying , subhra.mazumdar@oracle.com, Steven Sistare , jwadams@google.com, ashwinch@google.com, sqazi@google.com, Shakeel Butt , walken@google.com, rientjes@google.com, junaids@google.com, Neha Agarwal References: <1dc80ff6-f53f-ae89-be29-3408bf7d69cc@oracle.com> <01000165aa490dc9-64abf872-afd1-4a81-a46d-a50d0131de93-000000@email.amazonses.com> <839e2703-1588-0873-00a7-d04810f403cf@linux.vnet.ibm.com> From: Laurent Dufour Date: Thu, 6 Sep 2018 09:45:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18090607-0028-0000-0000-000002F5149E X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18090607-0029-0000-0000-000023AE98B0 Message-Id: <4d6a466c-6f77-b54e-fb30-9ad8e5bb4023@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-09-06_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1809060083 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/09/2018 01:01, Thomas Gleixner wrote: > On Wed, 5 Sep 2018, Laurent Dufour wrote: >> On 05/09/2018 17:10, Christopher Lameter wrote: >>> Large page sizes also reduce contention there. >> >> That's true for the page fault path, but for process's actions manipulating the >> memory process's layout (mmap,munmap,madvise,mprotect) the impact is minimal >> unless the code has to manipulate the page tables. > > And how exactly are you going to do any of those operations _without_ > manipulating the page tables? I agree, at one time the page tables would have to be manipulated, and this is mostly done under the protection of the page table locks - should the mmap_sem still being held then ? I was thinking about all the processing done on the VMAs, accounting, etc. That part, usually not manipulating the page tables, is less dependent of the underlying page size. But I agree at one time of the processing, the page table are manipulated and dealing with larger pages is better then. Thanks, Laurent.