From patchwork Mon Jun 7 19:54:18 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 12304563 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=-11.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 89CE1C47082 for ; Mon, 7 Jun 2021 19:54:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5AC6C611BD for ; Mon, 7 Jun 2021 19:54:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230425AbhFGT4j (ORCPT ); Mon, 7 Jun 2021 15:56:39 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:60541 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230351AbhFGT4i (ORCPT ); Mon, 7 Jun 2021 15:56:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623095686; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=E+GWkoi5o/3+tnBcPnBYmV0MPLfSi0TMmWvZba2R+/E=; b=jJpBmiB3tiIcIQD6YqWkdrzbh9Ycaz4wvRFqt9a03Z/Jsntb+UsFSgg+WCb666TMPJKPpY kuzUS3nmkrQXoEYnOmsqnC+WxupPtgMoe0hK7Tmesg07TpiVsA9Z7aRDlr5eFNT1E6ON0c VuWhXxLAoKH/UTzR9Jy4XXO07bBF9to= 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-416-Ep-RTuDENbWGYztZUkA75g-1; Mon, 07 Jun 2021 15:54:45 -0400 X-MC-Unique: Ep-RTuDENbWGYztZUkA75g-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E39CA2D0; Mon, 7 Jun 2021 19:54:42 +0000 (UTC) Received: from t480s.redhat.com (ovpn-112-9.ams2.redhat.com [10.36.112.9]) by smtp.corp.redhat.com (Postfix) with ESMTP id 07D7410013C1; Mon, 7 Jun 2021 19:54:30 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: David Hildenbrand , Andrew Morton , Vitaly Kuznetsov , "Michael S. Tsirkin" , Jason Wang , Marek Kedzierski , Hui Zhu , Pankaj Gupta , Wei Yang , Oscar Salvador , Michal Hocko , Dan Williams , Anshuman Khandual , Dave Hansen , Vlastimil Babka , Mike Rapoport , "Rafael J. Wysocki" , Len Brown , Pavel Tatashin , virtualization@lists.linux-foundation.org, linux-mm@kvack.org, linux-acpi@vger.kernel.org Subject: [PATCH v1 00/12] mm/memory_hotplug: "auto-movable" online policy and memory groups Date: Mon, 7 Jun 2021 21:54:18 +0200 Message-Id: <20210607195430.48228-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org Hi, this series aims at improving in-kernel auto-online support. It tackles the fundamental problems that: 1) We can create zone imbalances when onlining all memory blindly to ZONE_MOVABLE, in the worst case crashing the system. We have to know upfront how much memory we are going to hotplug such that we can safely enable auto-onlining of all hotplugged memory to ZONE_MOVABLE via "online_movable". This is far from practical and only applicable in limited setups -- like inside VMs under the RHV/oVirt hypervisor which will never hotplug more than 3 times the boot memory (and the limitation is only in place due to the Linux limitation). 2) We see more setups that implement dynamic VM resizing, hot(un)plugging memory to resize VM memory. In these setups, we might hotplug a lot of memory, but it might happen in various small steps in both directions (e.g., 2 GiB -> 8 GiB -> 4 GiB -> 16 GiB ...). virtio-mem is the primary driver of this upstream right now, performing such dynamic resizing NUMA-aware via multiple virtio-mem devices. Onlining all hotplugged memory to ZONE_NORMAL means we basically have no hotunplug guarantees. Onlining all to ZONE_MOVABLE means we can easily run into zone imbalances when growing a VM. We want a mixture, and we want as much memory as reasonable/configured in ZONE_MOVABLE. 3) Memory devices consist of 1..X memory block devices, however, the kernel doesn't really track the relationship. Consequently, also user space has no idea. We want to make per-device decisions. As one example, for memory hotunplug it doesn't make sense to use a mixture of zones within a single DIMM: we want all MOVABLE if possible, otherwise all !MOVABLE, because any !MOVABLE part will easily block the DIMM from getting hotunplugged. As another example, virtio-mem operates on individual units that span 1..X memory blocks. Similar to a DIMM, we want a unit to either be all MOVABLE or !MOVABLE. Further, we want as much memory of a virtio-mem device to be MOVABLE as possible. 4) We want memory onlining to be done right from the kernel while adding memory; for example, this is reqired for fast memory hotplug for drivers that add individual memory blocks, like virito-mem. We want a way to configure a policy in the kernel and avoid implementing advanced policies in user space. The auto-onlining support we have in the kernel is not sufficient. All we have is a) online everything movable (online_movable) b) online everything !movable (online_kernel) c) keep zones contiguous (online). This series allows configuring c) to mean instead "online movable if possible according to the coniguration, driven by a maximum MOVABLE:KERNEL ratio" -- a new onlining policy. This series does 3 things: 1) Introduces the "auto-movable" online policy that initially operates on individual memory blocks only. It uses a maximum MOVABLE:KERNEL ratio to make a decision whether a memory block will be onlined to ZONE_MOVABLE or not. However, in the basic form, hotplugged KERNEL memory does not allow for more MOVABLE memory (details in the patches). CMA memory is treated like MOVABLE memory. 2) Introduces static (e.g., DIMM) and dynamic (e.g., virtio-mem) memory groups and uses group information to make decisions in the "auto-movable" online policy accross memory blocks of a single memory device (modeled as memory group). 3) Maximizes ZONE_MOVABLE memory within dynamic memory groups, by allowing ZONE_NORMAL memory within a dynamic memory group to allow for more ZONE_MOVABLE memory within the same memory group. The target use case is dynamic VM resizing using virtio-mem. I remember that the basic idea of using a ratio to implement a policy in the kernel was once mentioned by Vitaly Kuznetsov, but I might be wrong (I lost the pointer to that discussion). For me, the main use case is using it along with virtio-mem (and DIMMs / ppc64 dlpar where necessary) for dynamic resizing of VMs, increasing the amount of memory we can hotunplug reliably again if we might eventually hotplug a lot of memory to a VM. The target usage will be: 1) Linux boots with "mhp_default_online_type=offline" 2) User space (e.g., systemd unit) configures memory onlining (according to a config file and system properties), for example: * Setting memory_hotplug.online_policy=auto-movable * Setting memory_hotplug.auto_movable_ratio=301 * Setting memory_hotplug.auto_movable_numa_aware=true 3) User space enabled auto onlining via "echo online > /sys/devices/system/memory/auto_online_blocks" 4) User space triggers manual onlining of all already-offline memory blocks (go over offline memory blocks and set them to "online") For DIMMs, hotplugging 4 GiB DIMMs to a 4 GiB VM with a configured ratio of 301% results in the following layout: Memory block 1-15: DMA32 (early) Memory block 32-47: Normal (early) Memory block 48-79: Movable (DIMM 0) Memory block 80-111: Movable (DIMM 1) Memory block 112-143: Movable (DIMM 2) Memory block 144-275: Normal (DIMM 3) Memory block 176-207: Normal (DIMM 4) ... all Normal (-> hotplugged Normal memory does not allow for more Movable memory) For virtio-mem, using a simple, single virtio-mem device with a 4 GiB VM will result in the following layout: Memory block 1-15: DMA32 (early) Memory block 32-47: Normal (early) Memory block 48-143: Movable (virtio-mem, first 12 GiB) Memory block 144: Normal (virtio-mem, next 128 MiB) Memory block 145-147: Movable (virtio-mem, next 384 MiB) Memory block 148: Normal (virtio-mem, next 128 MiB) Memory block 149-151: Movable (virtio-mem, next 384 MiB) ... Normal/Movable mixture as above (-> hotplugged Normal memory allows for more Movable memory within the same device) Which gives us maximum flexibility when dynamically growing/shrinking a VM in smaller steps. When shrinking, virtio-mem will prioritize unplug of MOVABLE memory with [1] sent last week, such that we won't accidentially trigger zone imbalances in more complicated setups that involve multiple virtio-mem devices. I'll update the memory-hotplug.rst documentation separately, once the overhaul is done. For now I decided to use module parameters that can be changed at runtime and not add new sysfs files for configuration. Easier and cleaner IMHO -- especially, temporarily overwritable via the cmdline. Future work: - Use a single static memory group for dax/kmem - Sense upfront for DIMMs (and dax/kmem) which pieces can actually be added and won't actually contribute to the static memory group size - Use memory groups for ppc64 dlpar - More tunables. For example, a way to configure to keep some memory default offline (s390x standby memory, dax/kmem) - Indicate to user space that MOVABLE might be a bad idea -- especially relevant when memory ballooning without support for balloon compaction is active. Cc: Andrew Morton Cc: Vitaly Kuznetsov Cc: "Michael S. Tsirkin" Cc: Jason Wang Cc: Marek Kedzierski Cc: Hui Zhu Cc: Pankaj Gupta Cc: Wei Yang Cc: Oscar Salvador Cc: Michal Hocko Cc: Dan Williams Cc: Anshuman Khandual Cc: Dave Hansen Cc: Vlastimil Babka Cc: Mike Rapoport Cc: "Rafael J. Wysocki" Cc: Len Brown Cc: Pavel Tatashin Cc: virtualization@lists.linux-foundation.org Cc: linux-mm@kvack.org Cc: linux-acpi@vger.kernel.org [1] https://lkml.kernel.org/r/20210602185720.31821-1-david@redhat.com David Hildenbrand (12): mm/memory_hotplug: use "unsigned long" for PFN in zone_for_pfn_range() mm: track present early pages per zone mm/memory_hotplug: introduce "auto-movable" online policy mm/memory_hotplug: remove nid parameter from arch_remove_memory() mm/memory_hotplug: remove nid parameter from remove_memory() and friends drivers/base/memory: "memory groups" to logically group memory blocks mm/memory_hotplug: track present pages in memory groups ACPI: memhotplug: memory resources cannot be enabled yet ACPI: memhotplug: use a single static memory group for a single memory device virtio-mem: use a single dynamic memory group for a single virtio-mem device mm/memory_hotplug: memory group aware "auto-movable" online policy mm/memory_hotplug: improved dynamic memory group aware "auto-movable" online policy arch/arm64/mm/mmu.c | 3 +- arch/ia64/mm/init.c | 3 +- arch/powerpc/mm/mem.c | 3 +- .../platforms/pseries/hotplug-memory.c | 9 +- arch/s390/mm/init.c | 3 +- arch/sh/mm/init.c | 3 +- arch/x86/mm/init_32.c | 3 +- arch/x86/mm/init_64.c | 3 +- drivers/acpi/acpi_memhotplug.c | 46 ++- drivers/base/memory.c | 163 +++++++-- drivers/dax/kmem.c | 3 +- drivers/virtio/virtio_mem.c | 26 +- include/linux/memory.h | 53 ++- include/linux/memory_hotplug.h | 35 +- include/linux/mmzone.h | 7 + mm/memory_hotplug.c | 346 +++++++++++++++++- mm/memremap.c | 5 +- mm/page_alloc.c | 3 + 18 files changed, 618 insertions(+), 99 deletions(-) base-commit: 614124bea77e452aa6df7a8714e8bc820b489922