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Thu, 06 Sep 2018 21:36:47 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w86LajCt027688 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 6 Sep 2018 21:36:45 GMT Received: from abhmp0011.oracle.com (abhmp0011.oracle.com [141.146.116.17]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w86Laf8H003298; Thu, 6 Sep 2018 21:36:42 GMT Received: from [192.168.1.164] (/50.38.38.67) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 06 Sep 2018 14:36:41 -0700 Subject: Re: Plumbers 2018 - Performance and Scalability Microconference To: "Huang, Ying" , Christopher Lameter Cc: 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, ldufour@linux.vnet.ibm.com, Pavel.Tatashin@microsoft.com, paulmck@linux.vnet.ibm.com, shady.issa@oracle.com, tariqt@mellanox.com, tglx@linutronix.de, tim.c.chen@intel.com, vbabka@suse.cz, longman@redhat.com, yang.shi@linux.alibaba.com, shy828301@gmail.com, 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 , Hugh Dickins References: <1dc80ff6-f53f-ae89-be29-3408bf7d69cc@oracle.com> <01000165aa490dc9-64abf872-afd1-4a81-a46d-a50d0131de93-000000@email.amazonses.com> <877ejzqtdy.fsf@yhuang-dev.intel.com> From: Mike Kravetz Message-ID: Date: Thu, 6 Sep 2018 14:36:38 -0700 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: <877ejzqtdy.fsf@yhuang-dev.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9008 signatures=668708 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=666 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1809060209 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/05/2018 06:58 PM, Huang, Ying wrote: > Hi, Christopher, > > Christopher Lameter writes: > >> On Tue, 4 Sep 2018, Daniel Jordan wrote: >> >>> - Promoting huge page usage: With memory sizes becoming ever larger, huge >>> pages are becoming more and more important to reduce TLB misses and the >>> overhead of memory management itself--that is, to make the system scalable >>> with the memory size. But there are still some remaining gaps that prevent >>> huge pages from being deployed in some situations, such as huge page >>> allocation latency and memory fragmentation. >> >> You forgot the major issue that huge pages in the page cache are not >> supported and thus we have performance issues with fast NVME drives that >> are now able to do 3Gbytes per sec that are only possible to reach with >> directio and huge pages. > > Yes. That is an important gap for huge page. Although we have huge > page cache support for tmpfs, we lacks that for normal file systems. > >> IMHO the huge page issue is just the reflection of a certain hardware >> manufacturer inflicting pain for over a decade on its poor users by not >> supporting larger base page sizes than 4k. No such workarounds needed on >> platforms that support large sizes. Things just zoom along without >> contortions necessary to deal with huge pages etc. >> >> Can we come up with a 2M base page VM or something? We have possible >> memory sizes of a couple TB now. That should give us a million or so 2M >> pages to work with. > > That sounds a good idea. Don't know whether someone has tried this. IIRC, Hugh Dickins and some others at Google tried going down this path. There was a brief discussion at LSF/MM. It is something I too would like to explore in my spare time. -- Mike Kravetz