From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB8A3C43334 for ; Thu, 6 Sep 2018 01:58:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A75D205F4 for ; Thu, 6 Sep 2018 01:58:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7A75D205F4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726356AbeIFGbV (ORCPT ); Thu, 6 Sep 2018 02:31:21 -0400 Received: from mga04.intel.com ([192.55.52.120]:13135 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725804AbeIFGbU (ORCPT ); Thu, 6 Sep 2018 02:31:20 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Sep 2018 18:58:25 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,334,1531810800"; d="scan'208";a="87578708" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.13.13]) by fmsmga001.fm.intel.com with ESMTP; 05 Sep 2018 18:58:18 -0700 From: "Huang\, Ying" To: Christopher Lameter Cc: Daniel Jordan , , "linux-mm\@kvack.org" , Aaron Lu , , , , , , , Dhaval Giani , , , , , , , , , , , , , , Steven Sistare , , , , Shakeel Butt , , , , Neha Agarwal Subject: Re: Plumbers 2018 - Performance and Scalability Microconference References: <1dc80ff6-f53f-ae89-be29-3408bf7d69cc@oracle.com> <01000165aa490dc9-64abf872-afd1-4a81-a46d-a50d0131de93-000000@email.amazonses.com> Date: Thu, 06 Sep 2018 09:58:17 +0800 In-Reply-To: <01000165aa490dc9-64abf872-afd1-4a81-a46d-a50d0131de93-000000@email.amazonses.com> (Christopher Lameter's message of "Wed, 5 Sep 2018 15:10:39 +0000") Message-ID: <877ejzqtdy.fsf@yhuang-dev.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. >> - Reducing the number of users of mmap_sem: This semaphore is frequently >> used throughout the kernel. In order to facilitate scaling this longstanding >> bottleneck, these uses should be documented and unnecessary users should be >> fixed. > > > Large page sizes also reduce contention there. Yes. >> If you haven't already done so, please let us know if you are interested in >> attending, or have suggestions for other attendees. > > Certainly interested in attending but this overlaps supercomputing 2018 in > Dallas Texas... Sorry to know this. It appears that there are too many conferences in November... Best Regards, Huang, Ying From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f198.google.com (mail-pl1-f198.google.com [209.85.214.198]) by kanga.kvack.org (Postfix) with ESMTP id 80DD36B7635 for ; Wed, 5 Sep 2018 21:58:27 -0400 (EDT) Received: by mail-pl1-f198.google.com with SMTP id a10-v6so4672572pls.23 for ; Wed, 05 Sep 2018 18:58:27 -0700 (PDT) Received: from mga02.intel.com (mga02.intel.com. [134.134.136.20]) by mx.google.com with ESMTPS id e4-v6si3800224pgk.630.2018.09.05.18.58.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Sep 2018 18:58:26 -0700 (PDT) From: "Huang\, Ying" Subject: Re: Plumbers 2018 - Performance and Scalability Microconference References: <1dc80ff6-f53f-ae89-be29-3408bf7d69cc@oracle.com> <01000165aa490dc9-64abf872-afd1-4a81-a46d-a50d0131de93-000000@email.amazonses.com> Date: Thu, 06 Sep 2018 09:58:17 +0800 In-Reply-To: <01000165aa490dc9-64abf872-afd1-4a81-a46d-a50d0131de93-000000@email.amazonses.com> (Christopher Lameter's message of "Wed, 5 Sep 2018 15:10:39 +0000") Message-ID: <877ejzqtdy.fsf@yhuang-dev.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Sender: owner-linux-mm@kvack.org List-ID: To: 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 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. >> - Reducing the number of users of mmap_sem: This semaphore is frequently >> used throughout the kernel. In order to facilitate scaling this longstanding >> bottleneck, these uses should be documented and unnecessary users should be >> fixed. > > > Large page sizes also reduce contention there. Yes. >> If you haven't already done so, please let us know if you are interested in >> attending, or have suggestions for other attendees. > > Certainly interested in attending but this overlaps supercomputing 2018 in > Dallas Texas... Sorry to know this. It appears that there are too many conferences in November... Best Regards, Huang, Ying