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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7947FC43334 for ; Wed, 20 Jul 2022 14:49:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240880AbiGTOts convert rfc822-to-8bit (ORCPT ); Wed, 20 Jul 2022 10:49:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238427AbiGTOtd (ORCPT ); Wed, 20 Jul 2022 10:49:33 -0400 X-Greylist: delayed 1951 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Wed, 20 Jul 2022 07:49:22 PDT Received: from mail2.intersystems.com (mail2.intersystems.com [38.105.105.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61214564F3 for ; Wed, 20 Jul 2022 07:49:21 -0700 (PDT) X-InterSystems: Sent from InterSystems X-InterSystems: Sent from InterSystems X-InterSystems: Sent from InterSystems X-InterSystems: Sent from InterSystems From: Ray Fucillo To: Mike Kravetz CC: linux-mm , "linux-kernel@vger.kernel.org" , Muchun Song , Michal Hocko , Peter Xu , Naoya Horiguchi , David Hildenbrand , "Aneesh Kumar K . V" , Andrea Arcangeli , "Kirill A . Shutemov" , Davidlohr Bueso , Prakash Sangappa , James Houghton , Mina Almasry , "Pasha Tatashin" , Axel Rasmussen , Ray Fucillo , Andrew Morton Subject: Re: [RFC PATCH v4 0/8] hugetlb: Change huge pmd sharing synchronization again Thread-Topic: [RFC PATCH v4 0/8] hugetlb: Change huge pmd sharing synchronization again Thread-Index: AQHYkXZV7rwY/0b1YEWM7yXbYs48gK2HptEA Date: Wed, 20 Jul 2022 14:16:46 +0000 Message-ID: <3F53322F-65B0-4DA0-84AB-360CB46769E4@intersystems.com> References: <20220706202347.95150-1-mike.kravetz@oracle.com> In-Reply-To: <20220706202347.95150-1-mike.kravetz@oracle.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [172.17.254.204] x-c2processedorg: 5d7e5ca7-6395-445f-80da-8568a4fc58e5 Content-Type: text/plain; charset="us-ascii" Content-ID: Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Jul 6, 2022, at 4:23 PM, Mike Kravetz wrote: > > I am sending this as a RFC once more in the hope of generating comments > and discussion. While the changes are intrusive, they do show a significant > performance benefit in my simulated workload. Code is based on next-20220706. > > hugetlb fault scalability regressions have recently been reported [1]. > This is not the first such report, as regressions were also noted when > commit c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing > synchronization") was added [2] in v5.7. At that time, a proposal to > address the regression was suggested [3] but went nowhere. > > The regression and benefit of this patch series is not evident when > using the vm_scalability benchmark reported in [2] on a recent kernel. > Results from running, Mike, thank you for all the work and careful consideration here! We did find that this patch set addresses the scalability regression that was at the root of critical issues for customers that upgraded to newer Linux distributions (those with commit c0d0381ade79) Ray