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=-1.0 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 EBB77C43444 for ; Thu, 17 Jan 2019 21:57:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C445D20868 for ; Thu, 17 Jan 2019 21:57:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727402AbfAQV5V (ORCPT ); Thu, 17 Jan 2019 16:57:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51994 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725889AbfAQV5V (ORCPT ); Thu, 17 Jan 2019 16:57:21 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A727AA7875; Thu, 17 Jan 2019 21:57:20 +0000 (UTC) Received: from segfault.boston.devel.redhat.com (segfault.boston.devel.redhat.com [10.19.60.26]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BDA6061B6C; Thu, 17 Jan 2019 21:57:18 +0000 (UTC) From: Jeff Moyer To: Keith Busch Cc: Dave Hansen , thomas.lendacky@amd.com, fengguang.wu@intel.com, dave@sr71.net, linux-nvdimm@lists.01.org, tiwai@suse.de, zwisler@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, baiyaowei@cmss.chinamobile.com, ying.huang@intel.com, bhelgaas@google.com, akpm@linux-foundation.org, bp@suse.de Subject: Re: [PATCH 0/4] Allow persistent memory to be used like normal RAM References: <20190116181859.D1504459@viggo.jf.intel.com> <20190117164736.GC31543@localhost.localdomain> <20190117193403.GD31543@localhost.localdomain> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 Date: Thu, 17 Jan 2019 16:57:17 -0500 In-Reply-To: <20190117193403.GD31543@localhost.localdomain> (Keith Busch's message of "Thu, 17 Jan 2019 12:34:03 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 17 Jan 2019 21:57:21 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Keith Busch writes: >> Keith, you seem to be implying that there are platforms that won't >> support memory mode. Do you also have some insight into how customers >> want to use this, beyond my speculation? It's really frustrating to see >> patch sets like this go by without any real use cases provided. > > Right, most NFIT reporting platforms today don't have memory mode, and > the kernel currently only supports the persistent DAX mode with these. > This series adds another option for those platforms. All NFIT reporting platforms today are shipping NVDIMM-Ns, where it makes absolutely no sense to use them as regular DRAM. I don't think that's a good argument to make. > I think numactl as you mentioned is the first consideration for how > customers may make use. Dave or Dan might have other use cases in mind. Well, it sure looks like this took a lot of work, so I thought there were known use cases or users asking for this functionality. Cheers, Jeff