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=-10.1 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL 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 DAC39C433E0 for ; Wed, 1 Jul 2020 19:50:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B592220720 for ; Wed, 1 Jul 2020 19:50:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="W8jEZt/v" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726925AbgGATu0 (ORCPT ); Wed, 1 Jul 2020 15:50:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44202 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726287AbgGATuZ (ORCPT ); Wed, 1 Jul 2020 15:50:25 -0400 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6BC3AC08C5C1 for ; Wed, 1 Jul 2020 12:50:25 -0700 (PDT) Received: by mail-pf1-x443.google.com with SMTP id j12so11431500pfn.10 for ; Wed, 01 Jul 2020 12:50:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=XJ3z9iA8O6dAIC+NJJ+9t4gOwZXNZKQoXN/EldNu944=; b=W8jEZt/vb01WxE/phfcnFCguMVUd3c09MDg/hlHySRsBL+LwESHKejygb7jhMXc6tl re3uPXxn/SXD+8nS2hdNIaIFnerkk4601BONkaQi7Iyn8ZAL3yYy9zHj3MmzTKTfpfBv 6jHMTspS2e2FYsB2oWVlWkPO4eEkYTlQhIc0yWq57rboPv+EHD4eAlpI8wgcDpREFDX8 OfzaCDsJ1U+t83oKfFz2qR/AEoeu7q68zlmYAp4efotqy07ep5c0/RzPtfr7f1fNcyDk gcMCVJuT8jL1G9iB3Brn4iVXSOX6l3JCQncGA4VDyqhypIYroLz4FPue4+gHJKABTCIT 4gFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version; bh=XJ3z9iA8O6dAIC+NJJ+9t4gOwZXNZKQoXN/EldNu944=; b=p2HhnT0JNYDU799Fckig0qK8L8HqXq9fzJ508/bL41ubDjzaWqWMmMfAVD66fcOivM vxWraqQUB+/lqvZz27IC3to1SX8rZSCau7zCWKw6tlQEJA/MBj2cWspFl8COKsZcjm1p Bp5qaNorEVc2OJyCXEF7TosxtON0pbbnyBANvO3BVs7XFL/+f3mr2weWkYzY3c6tO21u nwrpd3o4qujpdmkEZMKRyL+umBjH1Nt/9jNspxlIC79nuLbZ5H2BoeileQcNa4q3SSib udIHyAWlNSLLX2fxPjq0wP7qevKG3AYc4ukt80A1dtmrrYUgPLxh81CTJ+0WlaNhl+Kg uhoQ== X-Gm-Message-State: AOAM533sz3YGPOvIMxvseMWaGXXQT3emczMrJVZQVx9z2k8qnW5fLnHW HfHsw1tRQr95i06n5xX7JeOuwA== X-Google-Smtp-Source: ABdhPJxRTbwwfv5oYdmBH1GIXgyKUz+5jP5h9ldyt2NCMOtgGQHh83LNaVCxc4v//ByEcPimwVFF/Q== X-Received: by 2002:a63:4e62:: with SMTP id o34mr21804319pgl.208.1593633024808; Wed, 01 Jul 2020 12:50:24 -0700 (PDT) Received: from [2620:15c:17:3:4a0f:cfff:fe51:6667] ([2620:15c:17:3:4a0f:cfff:fe51:6667]) by smtp.gmail.com with ESMTPSA id j19sm5788338pjy.40.2020.07.01.12.50.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Jul 2020 12:50:23 -0700 (PDT) Date: Wed, 1 Jul 2020 12:50:23 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Dave Hansen cc: "Huang, Ying" , Yang Shi , Dave Hansen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kbusch@kernel.org, dan.j.williams@intel.com Subject: Re: [RFC][PATCH 3/8] mm/vmscan: Attempt to migrate page in lieu of discard In-Reply-To: <8182ede7-88ce-b891-d100-8c036130797e@intel.com> Message-ID: References: <20200629234503.749E5340@viggo.jf.intel.com> <20200629234509.8F89C4EF@viggo.jf.intel.com> <039a5704-4468-f662-d660-668071842ca3@linux.alibaba.com> <87h7urlioe.fsf@yhuang-dev.intel.com> <8182ede7-88ce-b891-d100-8c036130797e@intel.com> User-Agent: Alpine 2.23 (DEB 453 2020-06-18) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 1 Jul 2020, Dave Hansen wrote: > Even if they don't allocate directly from PMEM, is it OK for such an app > to get its cold data migrated to PMEM? That's a much more subtle > question and I suspect the kernel isn't going to have a single answer > for it. I suspect we'll need a cpuset-level knob to turn auto-demotion > on or off. > I think the answer is whether the app's cold data can be reclaimed, otherwise migration to PMEM is likely better in terms of performance. So any such app today should just be mlocking its cold data if it can't handle overhead from reclaim?