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=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_MED 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 94430C43334 for ; Wed, 5 Sep 2018 15:10:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4825D20861 for ; Wed, 5 Sep 2018 15:10:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazonses.com header.i=@amazonses.com header.b="YIL4BevO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4825D20861 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux.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 S1727660AbeIETlR (ORCPT ); Wed, 5 Sep 2018 15:41:17 -0400 Received: from a9-46.smtp-out.amazonses.com ([54.240.9.46]:45566 "EHLO a9-46.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726046AbeIETlR (ORCPT ); Wed, 5 Sep 2018 15:41:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug; d=amazonses.com; t=1536160239; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References:MIME-Version:Content-Type:Feedback-ID; bh=lsfLbHwBykz5/SXR183FmYEmB+8XC5HYqw0k1LBs37Q=; b=YIL4BevOO1zr6j4gYKlM3X6UYj97UxNgwqQQI81Mwtts1A2x25fBqaS70B8Yw//k QpUK3+i7FG1NfaJXIC/9pcLNaAGNcrO+xrrnjwSSyPgdzGUXy1N/TqBdL7G/TEA5uNQ iT64nzQKLRsE7RxMnp+IItQitrNlY4b0PXkWYuFM= Date: Wed, 5 Sep 2018 15:10:39 +0000 From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Daniel Jordan cc: 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, Huang Ying , brouer@redhat.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 Subject: Re: Plumbers 2018 - Performance and Scalability Microconference In-Reply-To: <1dc80ff6-f53f-ae89-be29-3408bf7d69cc@oracle.com> Message-ID: <01000165aa490dc9-64abf872-afd1-4a81-a46d-a50d0131de93-000000@email.amazonses.com> References: <1dc80ff6-f53f-ae89-be29-3408bf7d69cc@oracle.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-SES-Outgoing: 2018.09.05-54.240.9.46 Feedback-ID: 1.us-east-1.fQZZZ0Xtj2+TD7V5apTT/NrT6QKuPgzCT/IC7XYgDKI=:AmazonSES Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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. > - 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. > 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... From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) by kanga.kvack.org (Postfix) with ESMTP id A03656B73B9 for ; Wed, 5 Sep 2018 11:10:40 -0400 (EDT) Received: by mail-qk1-f198.google.com with SMTP id 123-v6so5381366qkl.3 for ; Wed, 05 Sep 2018 08:10:40 -0700 (PDT) Received: from a9-46.smtp-out.amazonses.com (a9-46.smtp-out.amazonses.com. [54.240.9.46]) by mx.google.com with ESMTPS id f24-v6si509800qkm.396.2018.09.05.08.10.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 05 Sep 2018 08:10:39 -0700 (PDT) Date: Wed, 5 Sep 2018 15:10:39 +0000 From: Christopher Lameter Subject: Re: Plumbers 2018 - Performance and Scalability Microconference In-Reply-To: <1dc80ff6-f53f-ae89-be29-3408bf7d69cc@oracle.com> Message-ID: <01000165aa490dc9-64abf872-afd1-4a81-a46d-a50d0131de93-000000@email.amazonses.com> References: <1dc80ff6-f53f-ae89-be29-3408bf7d69cc@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Daniel Jordan Cc: 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, Huang Ying brouer@redhat.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 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. 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. > - 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. > 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...