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 632FBC36014 for ; Wed, 2 Apr 2025 09:40:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 52CE2280005; Wed, 2 Apr 2025 05:39:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4D9FC280001; Wed, 2 Apr 2025 05:39:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3C8A1280005; Wed, 2 Apr 2025 05:39:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 1FE00280001 for ; Wed, 2 Apr 2025 05:39:58 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 444EBAB9A8 for ; Wed, 2 Apr 2025 09:39:59 +0000 (UTC) X-FDA: 83288607318.29.2F7144F Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf27.hostedemail.com (Postfix) with ESMTP id A634740009 for ; Wed, 2 Apr 2025 09:39:57 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=KE+8UrCx; spf=pass (imf27.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1743586797; 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=/VkULwase0F5Xk9ioJR0AhYz/seiWtr0/XmTj7X9SP0=; b=kixWpYF3s7vJojOkNtw9Wag51+ybVxSCXEpkrBSt63zQvuCFyJPfD/qaHcOYKzP/ESwYcp AqWslAW6cyEPnhBNaJJnsQBg2z/XmhWHw/Ls8KYINhjN0WXS/oPSaOjkvCqhKSZmDsChWR gGkgh6iBDGoBgvU41BGWzQ84IsYg88M= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=KE+8UrCx; spf=pass (imf27.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1743586797; a=rsa-sha256; cv=none; b=C/QSBSSKkHYHckjZIsGDDnmK0lTF0rqFU2MUmuCib26+BKlxZybMND3tsF+mcyf75n8+Iq p1BFdkpo8V5MCJkAStAs55wf40dn34Vxvf05ycV5FtQ5YxRIQpcOZpXWQ60z5bUyTb50DK QCKqJgkB4CyKcvQZmEq3yA/LVvjSVyw= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id E6EFF61360; Wed, 2 Apr 2025 09:39:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 36093C4CEE9; Wed, 2 Apr 2025 09:39:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1743586796; bh=SmCXw4v07fnCF2PMedutweCHBi3wxPPlB3+QMVFkasw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KE+8UrCxpQpzzo9nSQtehkHNB7tuKWLbhx5ScuFdQHr9Vy48cdtSapFzSd5/MzI46 TmsRR9Y4Qi1OSKhoQKGdy71N9j4c1QO2raQiRofMm7xpEnXrUZqJU2dDK1DZ9NrRsj diZGh5Wsr+G230J/VIof4zTVM7M0CA+TxufFTytfLJgpWqcDqrWI1lYYldFEbb2qhC a9F71uE4jfGVon9zoohpBmF+oWNNJZRL9Dh2IV8mnTMhmtG3v24TxOpttBy0XBDlpp IbH0GnGNeeMIXBrX2wYNJZKp25QcZycUk6brDJP90cyFSju7o/agepf1hDlvtEmBg7 CVWlRNZMEQHkA== Date: Wed, 2 Apr 2025 12:39:44 +0300 From: Mike Rapoport To: David Hildenbrand Cc: Oscar Salvador , Gregory Price , linux-mm@kvack.org, linux-acpi@vger.kernel.org, kernel-team@meta.com, x86@kernel.org, linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, rafael@kernel.org, lenb@kernel.org, gregkh@linuxfoundation.org, akpm@linux-foundation.org, dan.j.williams@intel.com, Jonathan.Cameron@huawei.com, alison.schofield@intel.com, rrichter@amd.com, bfaccini@nvidia.com, haibo1.xu@intel.com, dave.jiang@intel.com, Ira Weiny , Fan Ni Subject: Re: [PATCH v8 0/3] memory,x86,acpi: hotplug memory alignment advisement Message-ID: References: <20250127153405.3379117-1-gourry@gourry.net> <01d8cde7-0973-4303-bb5d-3d377a6862cb@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01d8cde7-0973-4303-bb5d-3d377a6862cb@redhat.com> X-Rspamd-Queue-Id: A634740009 X-Rspamd-Server: rspam05 X-Rspam-User: X-Stat-Signature: kgpu166puromnhafk8iuzdmx3ntxjufw X-HE-Tag: 1743586797-248314 X-HE-Meta: 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 NgUz+jui EPWUPCkIg/Qm8v+UaLiMZCOAum81XeQng7E7EgFstgmjsGOO2Ye6MExBqYuBstw4cewgZ3TO0Ka2+UMxI+mWhF2CLp/+VakT69iiROwvU6aYDvP2XBWL31KBZQ7xYtZk2PanjfhtMEVRKq720Zx4nOFcs8n5OsxpFBy70G+4cr+Dkg0TsiPLZPP0g47ohHh+6tokagc6F0xinx7750wJsgUZ61+3LdxmLgIAJt/3kqhUdCrOVYdgfi/0WV6jENSsEHF6i 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, Apr 01, 2025 at 09:08:31PM +0200, David Hildenbrand wrote: > On 01.04.25 20:53, Oscar Salvador wrote: > > On Mon, Jan 27, 2025 at 10:34:02AM -0500, Gregory Price wrote: > > > v8: nits and tag pickups > > > > > > When physical address regions are not aligned to memory block size, > > > the misaligned portion is lost (stranded capacity). > > > > > > Block size (min/max/selected) is architecture defined. Most architectures > > > tend to use the minimum block size or some simplistic heurist. On x86, > > > memory block size increases up to 2GB, and is otherwise fitted to the > > > alignment of non-hotplug (i.e. not special purpose memory). > > > > I wonder if something like this could help us in improving the > > ridiculous situation of having 16MB memory-block size on powerpc. > > They have this granularity because ... they want to add/remove memory in > 16MiB on some powerpc dlpar machines :( I'm not sure they do it today, there's a comment in near define of that 16M in arch/powerpc/mm/init_64.c: /* * Outside hotplug the kernel uses this value to map the kernel direct map * with radix. To be compatible with older kernels, let's keep this value * as 16M which is also SECTION_SIZE with SPARSEMEM. We can ideally map * things with 1GB size in the case where we don't support hotplug. */ and their SECTION_SIZE didn't change since 2005. Quite possible that they'll be fine with increasing their DEFAULT_MEMORY_BLOCK_SIZE. > probe_memory_block_size() can query the hypervisor on the actual hot(un)plug > size. IIRC, QEMU sets it to 256 MiB. > > -- > Cheers, > > David / dhildenb > -- Sincerely yours, Mike.