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 12B4FD2C55E for ; Tue, 22 Oct 2024 14:24:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 20BB96B0092; Tue, 22 Oct 2024 10:24:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1952B6B0095; Tue, 22 Oct 2024 10:24:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 00E8A6B0096; Tue, 22 Oct 2024 10:24:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id D022E6B0092 for ; Tue, 22 Oct 2024 10:24:09 -0400 (EDT) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 6E439A0115 for ; Tue, 22 Oct 2024 14:23:39 +0000 (UTC) X-FDA: 82701457356.12.00E9D70 Received: from mail-qt1-f182.google.com (mail-qt1-f182.google.com [209.85.160.182]) by imf25.hostedemail.com (Postfix) with ESMTP id 0C6B6A002E for ; Tue, 22 Oct 2024 14:23:55 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=gourry.net header.s=google header.b=aqldjm4g; dmarc=none; spf=pass (imf25.hostedemail.com: domain of gourry@gourry.net designates 209.85.160.182 as permitted sender) smtp.mailfrom=gourry@gourry.net ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1729607009; a=rsa-sha256; cv=none; b=X602TnKM00f4Qo4nDGz16EEI5y8D7oOKUIaLtLSrgzdLVuoH179lFtlKdMcyV/LE03JUkz IdvCQhbd39MBG4YxGXDsZCvgV8GmIGCjlR2/aoh89oN6ibX5hBS8SouLnEowfm5CBcVI+S b6QLt8eRZXBikawo6Eu8lIYkvHXp+eU= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=gourry.net header.s=google header.b=aqldjm4g; dmarc=none; spf=pass (imf25.hostedemail.com: domain of gourry@gourry.net designates 209.85.160.182 as permitted sender) smtp.mailfrom=gourry@gourry.net ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1729607009; 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:dkim-signature; bh=zSO/dlnnjdqEtRccDwku+xGxeoL8AGwZjql6S0C/leE=; b=V3bBSp5zh03sGtKS6SXLVPEbGzpNtoP5VfIGxMP/yGfMIWZTvmc+0AE4LsYJqzYOmpgmh/ JZaJgOko33w5x92q0VD/FTwC4aBGgVHfJeID9ltGZa/f9g7oVyaETw0ZyCBo07V6SiYRmy 5fgEEeFuQ9SmX63bddqBmog2RbZyaak= Received: by mail-qt1-f182.google.com with SMTP id d75a77b69052e-4603d3e4552so46012871cf.1 for ; Tue, 22 Oct 2024 07:24:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gourry.net; s=google; t=1729607046; x=1730211846; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=zSO/dlnnjdqEtRccDwku+xGxeoL8AGwZjql6S0C/leE=; b=aqldjm4ga8hk4yd55QiOFFqtHzdjDwQNH1mfx/G1NrWf2/bYuoKluEdVQQPBRCYZ0F aRP3R3ieZiLVwSljRROX/0c041UKSsaxlQZILiD7UHCLapcoPVNaaFkMV0Y7BuzaLFCC 3M+eMuVwc82HX2zOpi6cRAYMmmZB/Zwe4JCz5PWL5jH0tC7hYcMcrKHNFYuqr8bgg1dW YLVVUVHAgsdjwcIjWpmja04X/LZuUbjKyDrGKdw2UapbBTD+BjHAMWZ2ClTQAN1RHjws IA4KVPFsitNBu0ulU1xz37zA2fGYwylRfml9OhDHKZb5MTPxP1YgggNvYFEds/JU51QL zpFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729607046; x=1730211846; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=zSO/dlnnjdqEtRccDwku+xGxeoL8AGwZjql6S0C/leE=; b=Y7fOsIi8lREtLnwIDe/lHXrwYBMJGUNmDPB/xNe9TJKz/swPCALs71FSSteuYWJ9X4 KvzFeRuVxGjORE2xkVbde9KoE3b9RToBT9Oe+j6fuAPEkLeGV4hsmCmdeAbE+jd4CXYk 0W43C/OqdwHJWFlmesswwy2ttoqMLIz1ZhnCGPjAh1iaPM/Z7KiTntzDFI6ia+oJD0g9 0VSAglECqbWfxmY0i5FGIBlYpC0b5a3v/4dpDLrgEsknjLw3N3UgHO3Vcqa9Hku+ogCj CIId35Q7t/uHEarToY0Yo2NbWlBn/jUfysuDukppcyvi+c0WDzDcK0NYeWW7i3Udp5bE M73g== X-Forwarded-Encrypted: i=1; AJvYcCXTuNQoxvfrZkNZlE1ea4tQ28wcc4sUkEDUiZMbEoCD6xoyk4vLl8Mqs1596QIhRMYBWFGMfxgQ7w==@kvack.org X-Gm-Message-State: AOJu0YysQT3jKPIzeS0ak78fObue1hHm3Bk86Bi6Jc4BG2a/4tCbTc0Q jqdiItsQftorI1gXihD0NCpHFxB5ePTJE7heQYlM4Tq+cDUhGLquY8w9vpsmBBE= X-Google-Smtp-Source: AGHT+IF5fbaOto1AQAWktpGH/+6Tqp835/6zpFVXMyPZpiyi3+BOxKZkfPeAjgw/eug8GyrAW4p2RQ== X-Received: by 2002:ac8:5f07:0:b0:460:8f9a:9760 with SMTP id d75a77b69052e-460aed02689mr228595451cf.2.1729607046421; Tue, 22 Oct 2024 07:24:06 -0700 (PDT) Received: from PC2K9PVX.TheFacebook.com (pool-173-79-56-208.washdc.fios.verizon.net. [173.79.56.208]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-460d3d70a6bsm29593711cf.63.2024.10.22.07.24.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Oct 2024 07:24:05 -0700 (PDT) Date: Tue, 22 Oct 2024 10:24:07 -0400 From: Gregory Price To: David Hildenbrand Cc: Jonathan Cameron , linux-mm@kvack.org, linux-cxl@vger.kernel.org, Davidlohr Bueso , Ira Weiny , John Groves , virtualization@lists.linux.dev, Oscar Salvador , qemu-devel@nongnu.org, Dave Jiang , Dan Williams , linuxarm@huawei.com, wangkefeng.wang@huawei.com, John Groves , Fan Ni , Navneet Singh , =?utf-8?B?4oCcTWljaGFlbCBTLiBUc2lya2lu4oCd?= , Igor Mammedov , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= Subject: Re: [RFC] Virtualizing tagged disaggregated memory capacity (app specific, multi host shared) Message-ID: References: <20240815172223.00001ca7@Huawei.com> <1238f2a3-88a2-4996-92f2-05735801002b@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1238f2a3-88a2-4996-92f2-05735801002b@redhat.com> X-Rspam-User: X-Stat-Signature: a8n5siu957ab6nk741fbn9or8dfg4un5 X-Rspamd-Queue-Id: 0C6B6A002E X-Rspamd-Server: rspam02 X-HE-Tag: 1729607035-860239 X-HE-Meta: U2FsdGVkX183r+irEepmUfBPMIbBIm7MNUAauGBh5bOeH2x90gMbhs6qgb63CoiivR9kTYi7PBDpLKVTJZNfOS3Cj1F/f/oMa7sHnQHvC/lnLKrLfADLyqiBi1nIVnF61CKCpMqK/zVCXQdGydEeYhWOSyMqf0Hi8qh83jGwPteuMtgTuGt7KqNsqcmCeCl9KchE+WHuDH5AMg4wm4qjtK8T0KlaP4rTsUbXg3I0x8jxXO8AhPqHrigRoCeyVDmqE7UstrrCJ/2hTfPZDwJxkmRPEqQTDDZfLSFdzes5fPnoUJq1nESxfw+TH5Fv6u6vDZWQPwoUYbj4A3kD7J6LBeBAOVDxh0/Pt51AIPRhjlgz2YPYqKLAcNoxp2V1djEYv8w/m6dJ0iiitg+FmwX4TWGRDprWbx1f5Bx7yvW/JkEpS8p6n+Qm6EiRURvOfPoThuHfKqZmhQIN6i+biodzweO+IKZ2OxJgQtk5gxf7veYFuskP6TQ1/Ut1g8pN4q/xMjfm8uvOmOpk3sEd0sLmxvmuzJqhChHDIx89Git+64liAVC//ZNkUxutmX+bxDzhUSp8VQDUk5l0J/Un5mG7fVsMhpONbN//gLtEe2VvTchZlxE/fVFzcmdrDgCiLo3tAz7WyAXY9fiZCrF879khtpO8su+cgqzSY/UYT7LYBuILvnb3FAqvWo7b9BpfkJhebQFij/9Z7hXA9ElWpRsAdzuzqyoDe5TCS8axn0LWJodD0fl8qC145SEM0i9KKvkHP03p+pYCiQr4LWwbwpVy9RykbxRj/ym6Nbm3REeNqdkdNaJiuVTmVGR4+NR5QGXg4p3GXP+s7N+hS2rl/dqi325DggeuIFw/0NYvELO3kF0WFWXg3FtIhj8rPiFwm0R0DCud0x6BwnEb8zBKJy2/Z6sH43wey0B/9Gu0cmnhdWRcJJ0s8B/XDQTmdD95SDQvOiwyzcZGaC/hNgUJRgb jEJNJ4bB jnqqdGyFU3Fl6VelogUbFsEaKtqdQLEmfqQUV3qu2FQcgCZEho6w8Z3qx3M7sC7L8luEln7ZJoewAQqresqxjv1DxsqTn10BK6Z80wWgS2x5wsXDnrSF7Ncg9nv5dhAZPdzp2iPAW98MysY23BDQJH+DEG55Tk9owsye+NSKk7BKKu1VomjmKa7KgBBEUkljR7b4MN1AzuyVm4/khb5oAeI3iCgHYQExjdE00wgubmEHnx9+fevpZmHNODRpwqBm8Tok4tcCZD8xCs0cWKm+NALcHj50GhGHIPAG2 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 Tue, Oct 22, 2024 at 11:33:07AM +0200, David Hildenbrand wrote: > On 20.09.24 11:06, Gregory Price wrote: > > > The only concern is when insufficient ZONE_NORMAL exists to support > > ZONE_MOVABLE capacity - but this is unlikely to be the general scenario AND > > can be mitigated w/ existing mechanisms. > > It might be worthwhile looking at > Documentation/admin-guide/mm/memory-hotplug.rst "auto-movable" memory > onlining polciy. It might not fit all sue cases, though (just like > ZONE_MOVABLE doesn't) > I managed to miss auto-movable in my last pass through there. Though for our use-case, forcibly preventing ZONE_NORMAL for all CXL is the preferred option in an effort to keep as much kernel resources out of high latency memory. So I think we're just going to end up using memhp_default_state, and that'll be mostly fine. > > > > Manually onlined capacity defaults to ZONE_MOVABLE. > > > > It would be nice to make this behavior consistent, since the general opinion > > appears to be that this capacity should default to ZONE_MOVABLE. > > It's much easier to shoot yourself into the foot with ZONE_MOVABLE, that's > why the default can be adjusted manually using "online_movable" with e.g., > memhp_default_state. > > It's all a bit complicated, because there are various use cases and > mechanisms for memory hotplug ... IIRC RHEL defaults with its udev rules to > "ZONE_MOVABLE" on bare metal and "ZONE_NORMAL" in VMs. Except on s390, where > we default to "offline" (standby memory ....). > > I once worked on a systemd unit to make this configuration easier (and avoid > udev rules), and possibly more "automatic" depending on the detected > environment. > Appreciate the additional context, thanks! ~Gregory > -- > Cheers, > > David / dhildenb >