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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA953C47422 for ; Fri, 26 Jan 2024 20:41:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4D2F66B0087; Fri, 26 Jan 2024 15:41:25 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 483BB6B0088; Fri, 26 Jan 2024 15:41:25 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 371FC6B0089; Fri, 26 Jan 2024 15:41:25 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 285CF6B0087 for ; Fri, 26 Jan 2024 15:41:25 -0500 (EST) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id C647880965 for ; Fri, 26 Jan 2024 20:41:24 +0000 (UTC) X-FDA: 81722632488.01.0E4A68E Received: from gentwo.org (gentwo.org [62.72.0.81]) by imf01.hostedemail.com (Postfix) with ESMTP id 2716D4001F for ; Fri, 26 Jan 2024 20:41:22 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=linux.com (policy=none); spf=softfail (imf01.hostedemail.com: 62.72.0.81 is neither permitted nor denied by domain of cl@linux.com) smtp.mailfrom=cl@linux.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1706301683; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=MFCmtdi0AjlSKg20mgtOpVK7sV/RdliTv1cHwIhwgJQ=; b=2oJYWoLcn5lF4kqVnb2BAIvCELr+xnq1CJ3nAcOhzfCYaVpLYOXBAgY0myKQQ+hvJfUi1x MeaCFJCj1AdBtYmcpABiaVwGegxR9rhA+v0f9+1S5W0n2HEnJi518s8n+IcvgLHyJx0Py0 JP9QAnM0kg0dOF2mAzItBe4eTc267WY= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=linux.com (policy=none); spf=softfail (imf01.hostedemail.com: 62.72.0.81 is neither permitted nor denied by domain of cl@linux.com) smtp.mailfrom=cl@linux.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1706301683; a=rsa-sha256; cv=none; b=acfBTncVgDkrgEwBz3ZptjIUNw46m/JYV9qiytos6rj1ErhkcnhLtapQE2s4RhM/3POPsu Cg2rteDasDoHUobx4OLodmAra57EQjZxHcMrnJ3jP0Gc3hySdzbLFkKrOR+KpzJWjwZqb0 Yl1+tMNugaWLH0LInYLZEzONbqZUR24= Received: by gentwo.org (Postfix, from userid 1003) id B26DE40A98; Fri, 26 Jan 2024 12:41:21 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by gentwo.org (Postfix) with ESMTP id B142B40A96; Fri, 26 Jan 2024 12:41:21 -0800 (PST) Date: Fri, 26 Jan 2024 12:41:21 -0800 (PST) From: "Christoph Lameter (Ampere)" To: Matthew Wilcox cc: David Rientjes , John Hubbard , Zi Yan , Bharata B Rao , Dave Jiang , "Aneesh Kumar K.V" , "Huang, Ying" , Alistair Popple , Andrew Morton , Linus Torvalds , Dave Hansen , Mel Gorman , Jon Grimm , Gregory Price , Brian Morris , Wei Xu , Johannes Weiner , linux-mm@kvack.org Subject: Re: [RFC] Memory tiering kernel alignment In-Reply-To: Message-ID: <45d850ec-623b-7c07-c266-e948cdbf1f62@linux.com> References: <75f21150-1e12-4f4b-e578-e170e4fea18b@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed X-Rspam-User: X-Stat-Signature: za6nw1bee9xrqqwjgrpea416bxbgsijg X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 2716D4001F X-HE-Tag: 1706301682-419402 X-HE-Meta: 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 WYfXYyHM yt/WEX9O0EDTHF/RBaVUh3BLEaGA8+BOFHXuwX0G6ltfQrejRgq3QfG74XU+1OWRwykaz0DEaj+E4LSCbtToV1ydwJIUVZ/XQE2iGcqCweEMp9VfIfUp8MQAqrByLi1Y5mhXeB3Y5/Oi+nhj7Fp8JXLbUT70p063udvkFvXrt34+DRb9TWg0brlah2efzXUwPo+uVf/vD+aCTI4A= 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: List-Subscribe: List-Unsubscribe: On Thu, 25 Jan 2024, Matthew Wilcox wrote: > We should reject this technology before it harms our kernel and the > entire industry. There's a reason that SGI died. Nobody wants to buy > single image machines the size of a data centre. Some people with big pockets needed these data center sized single image machines. SGI died because Intel was not able to support large memory (petabytes!) anymore after they neglected to develop the processor that they promised contractually to SGI and therefore the tech became unusuable for the deep pocketed customers. The Linux kernel worked just fine with petabyte sized address spaces. There are certainly use cases for large memory pools. They can be created and have been improvised using RDMA. Basically shifting memory back and forth into the small memory processor spaces that Intel confined us in by taking sections of a simulated petabyte sized cross machine "address space" that is spread over lots of network nodes. CXL could perhaps allow us to come up with a better solution.