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[209.132.180.67]) by mx.google.com with ESMTP id e186-v6si3722057pfa.107.2018.09.05.19.01.12; Wed, 05 Sep 2018 19:01:28 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726308AbeIFGbV (ORCPT + 99 others); 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