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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 0B304C433DF for ; Fri, 21 Aug 2020 10:34:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BA001204EA for ; Fri, 21 Aug 2020 10:34:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="domLTO7T" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BA001204EA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3CB6D8D0025; Fri, 21 Aug 2020 06:34:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 32D9F8D0008; Fri, 21 Aug 2020 06:34:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1F7FE8D0025; Fri, 21 Aug 2020 06:34:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0166.hostedemail.com [216.40.44.166]) by kanga.kvack.org (Postfix) with ESMTP id 059C88D0008 for ; Fri, 21 Aug 2020 06:34:53 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id BCD991F06 for ; Fri, 21 Aug 2020 10:34:52 +0000 (UTC) X-FDA: 77174217624.08.robin33_3f0995a27038 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin08.hostedemail.com (Postfix) with ESMTP id 992021819E772 for ; Fri, 21 Aug 2020 10:34:52 +0000 (UTC) X-HE-Tag: robin33_3f0995a27038 X-Filterd-Recvd-Size: 5295 Received: from us-smtp-delivery-1.mimecast.com (us-smtp-2.mimecast.com [207.211.31.81]) by imf30.hostedemail.com (Postfix) with ESMTP for ; 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=20Pau=20Monn=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 Content-Type: text/plain; charset=UTF-8 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Rspamd-Queue-Id: 992021819E772 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 Content-Transfer-Encoding: quoted-printable 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: 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 o= ur add_memory*() interfaces with a flag, specifying that merging after addin= g 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 resour= ce 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(-) --=20 2.26.2