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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 518B6C433B4 for ; Fri, 7 May 2021 06:14:39 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CDF15613DD for ; Fri, 7 May 2021 06:14:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CDF15613DD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0F82B6B0092; Fri, 7 May 2021 02:14:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0A8C96B0093; Fri, 7 May 2021 02:14:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E8AC16B0095; Fri, 7 May 2021 02:14:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0233.hostedemail.com [216.40.44.233]) by kanga.kvack.org (Postfix) with ESMTP id C98806B0092 for ; Fri, 7 May 2021 02:14:37 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 79F5F8249980 for ; Fri, 7 May 2021 06:14:37 +0000 (UTC) X-FDA: 78113420994.02.40D658E Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by imf04.hostedemail.com (Postfix) with ESMTP id 2916B3C8 for ; Fri, 7 May 2021 06:14:28 +0000 (UTC) IronPort-SDR: Kg64ppzbovXMGN/GwFDtvAqkP8NLrNwKUkafmPvewVosv6Z2yhbKUzdc4pxVv0suMx56LByMn4 dAd8XCJgDoag== X-IronPort-AV: E=McAfee;i="6200,9189,9976"; a="259937027" X-IronPort-AV: E=Sophos;i="5.82,279,1613462400"; d="scan'208";a="259937027" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 May 2021 23:14:29 -0700 IronPort-SDR: UBtL/btF+damZ06lGSeBGO6WKVyRXVKQtOjBI2dEJcsxulyeLT4w+LkwdVSXayCfqdgqmHwS6V ++p9ZtrKDSUw== X-IronPort-AV: E=Sophos;i="5.82,279,1613462400"; d="scan'208";a="389914662" Received: from yhuang6-desk1.sh.intel.com (HELO yhuang6-desk1.ccr.corp.intel.com) ([10.239.13.1]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 May 2021 23:14:26 -0700 From: "Huang, Ying" To: Michal Hocko Cc: Dave Hansen , Dave Hansen , linux-mm@kvack.org, linux-kernel@vger.kernel.org, yang.shi@linux.alibaba.com, rientjes@google.com, dan.j.williams@intel.com, david@redhat.com, osalvador@suse.de, weixugc@google.com Subject: Re: [PATCH 00/10] [v7][RESEND] Migrate Pages in lieu of discard References: <20210401183216.443C4443@viggo.jf.intel.com> <9cd0dcde-f257-1b94-17d0-f2e24a3ce979@intel.com> Date: Fri, 07 May 2021 14:14:24 +0800 In-Reply-To: (Michal Hocko's message of "Fri, 16 Apr 2021 17:02:23 +0200") Message-ID: <87y2crnk8v.fsf@yhuang6-desk1.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Queue-Id: 2916B3C8 Authentication-Results: imf04.hostedemail.com; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=intel.com (policy=none); spf=none (imf04.hostedemail.com: domain of ying.huang@intel.com has no SPF policy when checking 134.134.136.31) smtp.mailfrom=ying.huang@intel.com X-Rspamd-Server: rspam04 X-Stat-Signature: byxd7ohu3e6bqikykqg8jn9m5jbxsim6 Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf04; identity=mailfrom; envelope-from=""; helo=mga06.intel.com; client-ip=134.134.136.31 X-HE-DKIM-Result: none/none X-HE-Tag: 1620368068-219451 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi, Michal, Michal Hocko writes: [...] >> >> > Btw. do you have any numbers from running this with some real work >> > workload? >> >> Yes, quite a bit. Do you have a specific scenario in mind? Folks seem >> to come at this in two different ways: >> >> Some want to know how much DRAM they can replace by buying some PMEM. >> They tend to care about how much adding the (cheaper) PMEM slows them >> down versus (expensive) DRAM. They're making a cost-benefit call >> >> Others want to repurpose some PMEM they already have. They want to know >> how much using PMEM in this way will speed them up. They will basically >> take any speedup they can get. >> >> I ask because as a kernel developer with PMEM in my systems, I find the >> "I'll take what I can get" case more personally appealing. But, the >> business folks are much more keen on the "DRAM replacement" use. Do you >> have any thoughts on what you would like to see? > > I was thinking about typical large in memory processing (e.g. in memory > databases) where the hot part of the working set is only a portion and > spilling over to a slower memory can be still benefitial because IO + > data preprocessing on cold data is much slower. We have tested the patchset with the postgresql and pgbench. On a machine with DRAM and PMEM, the kernel with the patchset can improve the score of pgbench up to 22.1% compared with that of the DRAM only + disk case. This comes from the reduced disk read throughput (which reduces up to 70.8%). Best Regards, Huang, Ying