From patchwork Fri Aug 21 10:34:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11728839 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 897BC16B1 for ; Fri, 21 Aug 2020 10:36:25 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6618F20738 for ; Fri, 21 Aug 2020 10:36:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="domLTO7T" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6618F20738 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k94Nr-0000Xs-7Y; Fri, 21 Aug 2020 10:34:55 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k94Nq-0000Xn-68 for xen-devel@lists.xenproject.org; Fri, 21 Aug 2020 10:34:54 +0000 X-Inumbo-ID: b22fe96b-4dbe-4699-b0fb-8eecdad194f0 Received: from us-smtp-delivery-124.mimecast.com (unknown [216.205.24.124]) by us1-rack-iad1.inumbo.com (Halon) with ESMTP id b22fe96b-4dbe-4699-b0fb-8eecdad194f0; Fri, 21 Aug 2020 10:34:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598006091; h=from:from: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:content-transfer-encoding; bh=Lz1Dlp3n64jbr0nqc1nHMGKoG4tO/ALxoWb8NdfDDro=; b=domLTO7T0SoEgJNLvoTf5fxtxm7/j/b/PjYBNPAWSQvtncee6HUCUlFZiq/u5kkhamEbac hXYfmaM2s+D3E9gWdjUSca2fFOSRcOMJKpfp0lA7CiujOzAwGk35sEdcrc1IS6A0zGc5CJ QUTv78gqQ2+geCdDAvOO2pM/vpFIog0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-337-tNVl4_PKOqOy6s0hWbWRxQ-1; Fri, 21 Aug 2020 06:34:47 -0400 X-MC-Unique: tNVl4_PKOqOy6s0hWbWRxQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7C4AA100CF73; Fri, 21 Aug 2020 10:34:44 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-87.ams2.redhat.com [10.36.114.87]) by smtp.corp.redhat.com (Postfix) with ESMTP id D2F07756D7; Fri, 21 Aug 2020 10:34:32 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: virtualization@lists.linux-foundation.org, linux-mm@kvack.org, linux-hyperv@vger.kernel.org, xen-devel@lists.xenproject.org, David Hildenbrand , Andrew Morton , Ard Biesheuvel , Baoquan He , Boris Ostrovsky , Dan Williams , Haiyang Zhang , Jason Gunthorpe , Jason Wang , Juergen Gross , Julien Grall , Kees Cook , "K. Y. Srinivasan" , "Michael S. Tsirkin" , Michal Hocko , Pankaj Gupta , =?utf-8?q?Roger_Pau_Monn=C3=A9?= , Stefano Stabellini , Stephen Hemminger , Thomas Gleixner , Wei Liu , Wei Yang Subject: [PATCH v1 0/5] mm/memory_hotplug: selective merging of system ram resources Date: Fri, 21 Aug 2020 12:34:26 +0200 Message-Id: <20200821103431.13481-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" This is the follow-up of "[PATCH RFCv1 0/5] mm/memory_hotplug: selective merging of memory resources" [1] Some add_memory*() users add memory in small, contiguous memory blocks. Examples include virtio-mem, hyper-v balloon, and the XEN balloon. This can quickly result in a lot of memory resources, whereby the actual resource boundaries are not of interest (e.g., it might be relevant for DIMMs, exposed via /proc/iomem to user space). We really want to merge added resources in this scenario where possible. Resources are effectively stored in a list-based tree. Having a lot of resources not only wastes memory, it also makes traversing that tree more expensive, and makes /proc/iomem explode in size (e.g., requiring kexec-tools to manually merge resources when creating a kdump header. The current kexec-tools resource count limit does not allow for more than ~100GB of memory with a memory block size of 128MB on x86-64). Let's allow to selectively merge system ram resources directly below a specific parent resource. Patch #3 contains a /proc/iomem example. Only tested with virtio-mem. Note: This gets the job done and is comparably simple. More complicated approaches would require introducing IORESOURCE_MERGEABLE and extending our add_memory*() interfaces with a flag, specifying that merging after adding succeeded is acceptable. I'd like to avoid that complexity and code churn for now. [1] https://lkml.kernel.org/r/20200731091838.7490-1-david@redhat.com RFC -> v1: - Switch from rather generic "merge_child_mem_resources()" where a resource name has to be specified to "merge_system_ram_resources(). - Smaller comment/documentation/patch description changes/fixes David Hildenbrand (5): kernel/resource: make release_mem_region_adjustable() never fail kernel/resource: merge_system_ram_resources() to merge resources after hotplug virtio-mem: try to merge system ram resources xen/balloon: try to merge system ram resources hv_balloon: try to merge system ram resources drivers/hv/hv_balloon.c | 3 ++ drivers/virtio/virtio_mem.c | 14 ++++- drivers/xen/balloon.c | 4 ++ include/linux/ioport.h | 7 ++- kernel/resource.c | 101 ++++++++++++++++++++++++++++-------- mm/memory_hotplug.c | 22 +------- 6 files changed, 105 insertions(+), 46 deletions(-)