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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 6C6C3C43381 for ; Wed, 27 Mar 2019 20:35:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 23AE52054F for ; Wed, 27 Mar 2019 20:35:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="fwqIWCOy" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 23AE52054F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B79116B0007; Wed, 27 Mar 2019 16:35:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B4E1D6B0008; Wed, 27 Mar 2019 16:35:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A650F6B000A; Wed, 27 Mar 2019 16:35:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-pg1-f197.google.com (mail-pg1-f197.google.com [209.85.215.197]) by kanga.kvack.org (Postfix) with ESMTP id 7113D6B0007 for ; Wed, 27 Mar 2019 16:35:33 -0400 (EDT) Received: by mail-pg1-f197.google.com with SMTP id e12so10711955pgh.2 for ; Wed, 27 Mar 2019 13:35:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:from:to:cc:subject :message-id:references:mime-version:content-disposition:in-reply-to :user-agent; bh=QPOloOxRTaTdLOpUVbW+jky/YMc8w2U+BABUuwfTLpA=; b=K8sWKVkZ0H/ay45d0ffsgqwDb12IpMioRK2KqJuhaMIigizt6rs/q2PG3irlaO67Db vD9RG4S7rXyBj0xMXTfaIREAk76E0DLtX9/EpyHa7y/nSwoC6v6XioDgV6Yq9QlbVnQY oYYjC26TGhybOBB3LuxwfHQsiPb+U/B16WYv9IK9jtC/StgE5ZCcz35DhMZ8Ln1qdUnz EN0mXiJ+jT4lY4nHNHDwbGNnCGxYfMiUlUVcs9xFQfKwIATOhHjttgIV2rb2WEtDYNdZ 4DfTgnPEqQ2G80xP89RVPdNqPVSe5QBAEnFh5sQmaUOQzyZtT6szoBkCM+Br6E+aUxRP uv9w== X-Gm-Message-State: APjAAAUAlrUOc2Ou/VQQWz8vFSBQvR6hzjfrgsHxOLLr1xtqnJbe8Bso Km9epbfh8IKUDulIx/8WB3G2Wk1Gu6NGlxTZeUlu1eAbZzSz/CVOWVtVlKgK68r0EdvWiciFyvl CQVfy6R/mvOmXZY005QQ5hUayOCZZogvOpUiApFuy6wgt2IXbdb/gky6VthRMgH9m9Q== X-Received: by 2002:a17:902:7289:: with SMTP id d9mr38570053pll.314.1553718933072; Wed, 27 Mar 2019 13:35:33 -0700 (PDT) X-Google-Smtp-Source: APXvYqz3cnLiWjrMiqcuGzLr9KoHLpYLHDK521XJMiqwhaARTBmraDfQ5yQy9K/UUvom4VO7/BP8 X-Received: by 2002:a17:902:7289:: with SMTP id d9mr38570019pll.314.1553718932375; Wed, 27 Mar 2019 13:35:32 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1553718932; cv=none; d=google.com; s=arc-20160816; b=qnImmscWKvVrxo/OSz2Rzwr05D3637j1UcRz0ovZDlhAfCWoBtJJ+iE3gw4QRCVQ/0 WX7SMd36Z3/JUeYaWUCznAaS8DKAQuQen+lj78EGeNmZO/WfZkqwTo8A/DKRfvWVWVWb JExsousjqqe9jLty+slGGZZKjINeulF/ZyH8VF7+YP1prSWJxapCRE88qRedhYEIQW2k CCd5I08r3rmKHsnNsl3cKoU/d/WTB3U3ginBrW8z19wa5bfrRtPR8KbVT4YM+XcWYx+A 14p+X8lR6lGyqeciYv6UXRBej83SxecDvxMHhld3b6u02ejHoVbNjS3h3iAB1BS1NYvI mKDw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature; bh=QPOloOxRTaTdLOpUVbW+jky/YMc8w2U+BABUuwfTLpA=; b=zxnNYA0wMCRw2igG2l7ywgqphjKIyaEXlfgbMiwPQGYnps/TJ2qztfMe66oX9WlN7N hQi9SrMXaf7JNBEbdBKsT0Roq1/i0S7R1pTu7aTW/pKyFz/U2jxL+Ez9DgKijSfLjfUk WUQ/IColNTlK5FQKzN2H9O/tboln0ZhPqb/e4MCgVSRLQTd+QO1Cjv5G/XllZrZh3iSJ cJv4c0x7V+SQmSX6z/xsrSXLaCIGOwoSsQX1vrldhDmHqUW+jzgjDEp4Yltgq/Y/G8gV 218PCCtQ9N+nCIhUVyTWfY3v/YxaKxa7ZvqjXV0k+vemHZQXqJSShWZ4kvTAbmp8WLef DLXg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=fwqIWCOy; spf=pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=willy@infradead.org Received: from bombadil.infradead.org (bombadil.infradead.org. [2607:7c80:54:e::133]) by mx.google.com with ESMTPS id i33si8295857pgb.99.2019.03.27.13.35.32 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 27 Mar 2019 13:35:32 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=fwqIWCOy; spf=pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=willy@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=QPOloOxRTaTdLOpUVbW+jky/YMc8w2U+BABUuwfTLpA=; b=fwqIWCOyonfUBxY/jYxMe7Cta LrKDdKpoPiEiX7TXLGKbtSDRk/5QtQcNckocOCp8bTsUWepcPLwBuOqq+/xDvMEF0e+QopEX7cANr JoeMqtKfG8rbY1K3WEx87Da5m0eAaf9B8ttoJA2eDYrgHbS4IJ+Uz4vfee4bsIHsRezaMTFyIM5k4 M7X+3il7hPr53Ks7kLecEjfE0hxw+RM8yd3estaG1wS7OUN7aDUIBasLdDqt3UultvUAFs1FvxzIj GZ23+02PfyUH5M0xsQGPoZWMQQr2saeEdpTLMAcGWdUMkQZnLaDb714B7QWoF3YcoW0lWU4jLbxFk Kx7LMerQA==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1h9FGa-0006KX-GT; Wed, 27 Mar 2019 20:35:20 +0000 Date: Wed, 27 Mar 2019 13:35:20 -0700 From: Matthew Wilcox To: Dan Williams Cc: Michal Hocko , Yang Shi , Mel Gorman , Rik van Riel , Johannes Weiner , Andrew Morton , Dave Hansen , Keith Busch , Fengguang Wu , "Du, Fan" , "Huang, Ying" , Linux MM , Linux Kernel Mailing List Subject: Re: [RFC PATCH 0/10] Another Approach to Use PMEM as NUMA Node Message-ID: <20190327203520.GU10344@bombadil.infradead.org> References: <1553316275-21985-1-git-send-email-yang.shi@linux.alibaba.com> <20190326135837.GP28406@dhcp22.suse.cz> <43a1a59d-dc4a-6159-2c78-e1faeb6e0e46@linux.alibaba.com> <20190326183731.GV28406@dhcp22.suse.cz> <20190327090100.GD11927@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) 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: On Wed, Mar 27, 2019 at 10:34:11AM -0700, Dan Williams wrote: > On Wed, Mar 27, 2019 at 2:01 AM Michal Hocko wrote: > > No, Linux NUMA implementation makes all numa nodes available by default > > and provides an API to opt-in for more fine tuning. What you are > > suggesting goes against that semantic and I am asking why. How is pmem > > NUMA node any different from any any other distant node in principle? > > Agree. It's just another NUMA node and shouldn't be special cased. > Userspace policy can choose to avoid it, but typical node distance > preference should otherwise let the kernel fall back to it as > additional memory pressure relief for "near" memory. I think this is sort of true, but sort of different. These are essentially CPU-less nodes; there is no CPU for which they are fast memory. Yes, they're further from some CPUs than from others. I have never paid attention to how Linux treats CPU-less memory nodes, but it would make sense to me if we don't default to allocating from remote nodes. And treating pmem nodes as being remote from all CPUs makes a certain amount of sense to me. eg on a four CPU-socket system, consider this as being pmem1 --- node1 --- node2 --- pmem2 | \ / | | X | | / \ | pmem3 --- node3 --- node4 --- pmem4 which I could actually see someone building with normal DRAM, and we should probably handle the same way as pmem; for a process running on node3, allocate preferentially from node3, then pmem3, then other nodes, then other pmems.