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 B9611C28D13 for ; Sat, 20 Aug 2022 01:55:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1929F6B0075; Fri, 19 Aug 2022 21:55:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 141DF8D0002; Fri, 19 Aug 2022 21:55:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0091F6B007B; Fri, 19 Aug 2022 21:55:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id E3A426B0075 for ; Fri, 19 Aug 2022 21:55:03 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id B8704140136 for ; Sat, 20 Aug 2022 01:55:03 +0000 (UTC) X-FDA: 79818302886.30.34ADB19 Received: from mail-pf1-f181.google.com (mail-pf1-f181.google.com [209.85.210.181]) by imf28.hostedemail.com (Postfix) with ESMTP id 73DFEC0035 for ; Sat, 20 Aug 2022 01:55:02 +0000 (UTC) Received: by mail-pf1-f181.google.com with SMTP id x19so2957741pfq.1 for ; Fri, 19 Aug 2022 18:55:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc; bh=7qNRmSKx6dng0szgtUPCAb9wPBSkj9/hqnB/dGOA0x8=; b=hoOjndKnE52oxuIUy/R8MbMIkCf8KHxfspEl7kcwdgnq1l9x/26u6kIVged2a5qpno gXGJb9tr6UOaXk/9ZdUGntNTm9GRnKFMMRop1Rf9j+Dvn5veCL3wl8YsRNs3SFsHjm/R U2jt9wJ35hdNQmZFnYMgmo17/dY2u02GGygHGrO90AkTiCMYQ1wAyYDHSVybOmbiTDi3 y+T5EGoNiCzeYQDJU2WBDulqpnKp0R3xLHe/Z0LGyxOQyx0ZcuXIlakN7aMLhQGWW3oB kT5fyTTuIi69ZyIgHnx+o1UtNmo0cAYIvDJXMrg0jjpjjhG6mPCreqUkpBKv13fPKvOU XTSQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc; bh=7qNRmSKx6dng0szgtUPCAb9wPBSkj9/hqnB/dGOA0x8=; b=6pCkSMkZ2NuCah7ap24IPQ2TvZKJVIzvQAqGyyD24yXbFEg1dlqQnfLyOp5RPbLq8T KJSSzBgsRx/yTEzlruuJ2bIg1AN6gmQTcw2B/4umo5kw5DKrLh6u1ZFEb+T9IvgVhjL0 VPy0e7oIgunyruEdgmOlJnh9GDZ2Y06vd/TuNqe6yFPB/DlvdFqfsPH/xv/Lgry/LvVj LrZHq3kji1Q8byvWE/t6M/lPDorWrkI+ZI3u5ZHMl28mZXFj/7KkvDqMBjJ6kDYdJEij SYI9z5LuzNZ2OG3TohxgTqujEjYYINFGlueNFmQ18hF4RdPQqCPrfaybiFODg0epjYDW 5mSA== X-Gm-Message-State: ACgBeo2ULJmHl7WMWpOecT2hCnREmeSorVuDimFc7kWYYqzIxXl77LdS 3SpzgJLOXrJgfBq1FtX0z0CDfTzq7jb4jD205BgFkw== X-Google-Smtp-Source: AA6agR69IPi5cJ5qGkhCbV3mOm8p+BXNAadc91YDgoEpjqK3WJMI91Rwyvhi/EvFxaLiPk61rGNmHf7L2ghHSZ+0ZMI= X-Received: by 2002:a05:6a00:1a14:b0:52d:3e35:5b38 with SMTP id g20-20020a056a001a1400b0052d3e355b38mr10602325pfv.11.1660960501200; Fri, 19 Aug 2022 18:55:01 -0700 (PDT) MIME-Version: 1.0 References: <20220818131042.113280-1-aneesh.kumar@linux.ibm.com> In-Reply-To: <20220818131042.113280-1-aneesh.kumar@linux.ibm.com> From: Wei Xu Date: Fri, 19 Aug 2022 18:54:49 -0700 Message-ID: Subject: Re: [PATCH v15 00/10] mm/demotion: Memory tiers and demotion To: "Aneesh Kumar K.V" Cc: Linux MM , Andrew Morton , Huang Ying , Yang Shi , Davidlohr Bueso , Tim C Chen , Michal Hocko , Linux Kernel Mailing List , Hesham Almatary , Dave Hansen , Jonathan Cameron , Alistair Popple , Dan Williams , Johannes Weiner , jvgediya.oss@gmail.com, Bharata B Rao Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660960502; a=rsa-sha256; cv=none; b=lcDEAonYOqVInOZ8OEnMqZRr41GmZK1ikqpKvBKoy/drt79vZI+y/2J2zunuSPcsBpKmlY BaUd9ZaCX9CNlNj2Yc8gFE7qNDhhUc3ReVaNz+MHy6zm5skQrC7kaayyK2WAPLbDrxlEds S2xUjko6D9r9iUnEhj6rB64V/0H1Fws= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=hoOjndKn; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf28.hostedemail.com: domain of weixugc@google.com designates 209.85.210.181 as permitted sender) smtp.mailfrom=weixugc@google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660960502; 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=7qNRmSKx6dng0szgtUPCAb9wPBSkj9/hqnB/dGOA0x8=; b=1tf2f8xVvVjDrh8EL0AOl0B88CYs44ljc/aDZG+4fwyw5QqlomeltqXJdW5Gs7JwfMcW+Y ck6adl/dVlqFIJ/u9iZSToHl/XfDyybWnNT77ggIwtTYc0a2okCXE7hJDK51WeuywQRcdm Vv1X6GHol4ZEdMb+yCrggVv83hxgi/k= X-Stat-Signature: imi49gpnq58f9camjimdwsstjnuzqjya X-Rspamd-Queue-Id: 73DFEC0035 Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=hoOjndKn; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf28.hostedemail.com: domain of weixugc@google.com designates 209.85.210.181 as permitted sender) smtp.mailfrom=weixugc@google.com X-Rspamd-Server: rspam03 X-Rspam-User: X-HE-Tag: 1660960502-89105 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: Acked-by: Wei Xu On Thu, Aug 18, 2022 at 6:10 AM Aneesh Kumar K.V wrote: > > The current kernel has the basic memory tiering support: Inactive pages on a > higher tier NUMA node can be migrated (demoted) to a lower tier NUMA node to > make room for new allocations on the higher tier NUMA node. Frequently accessed > pages on a lower tier NUMA node can be migrated (promoted) to a higher tier NUMA > node to improve the performance. > > In the current kernel, memory tiers are defined implicitly via a demotion path > relationship between NUMA nodes, which is created during the kernel > initialization and updated when a NUMA node is hot-added or hot-removed. The > current implementation puts all nodes with CPU into the highest tier, and builds the > tier hierarchy tier-by-tier by establishing the per-node demotion targets based > on the distances between nodes. > > This current memory tier kernel implementation needs to be improved for several > important use cases: > > * The current tier initialization code always initializes each memory-only NUMA > node into a lower tier. But a memory-only NUMA node may have a high > performance memory device (e.g. a DRAM-backed memory-only node on a virtual > machine) and that should be put into a higher tier. > > * The current tier hierarchy always puts CPU nodes into the top tier. But on a > system with HBM (e.g. GPU memory) devices, these memory-only HBM NUMA nodes > should be in the top tier, and DRAM nodes with CPUs are better to be placed > into the next lower tier. > > * Also because the current tier hierarchy always puts CPU nodes into the top > tier, when a CPU is hot-added (or hot-removed) and triggers a memory node from > CPU-less into a CPU node (or vice versa), the memory tier hierarchy gets > changed, even though no memory node is added or removed. This can make the > tier hierarchy unstable and make it difficult to support tier-based memory > accounting. > > * A higher tier node can only be demoted to nodes with shortest distance on the > next lower tier as defined by the demotion path, not any other node from any > lower tier. This strict, demotion order does not work in all use > cases (e.g. some use cases may want to allow cross-socket demotion to another > node in the same demotion tier as a fallback when the preferred demotion node > is out of space), and has resulted in the feature request for an interface to > override the system-wide, per-node demotion order from the userspace. This > demotion order is also inconsistent with the page allocation fallback order > when all the nodes in a higher tier are out of space: The page allocation can > fall back to any node from any lower tier, whereas the demotion order doesn't > allow that. > > This patch series make the creation of memory tiers explicit under > the control of device driver. > > Memory Tier Initialization > ========================== > > Linux kernel presents memory devices as NUMA nodes and each memory device is of > a specific type. The memory type of a device is represented by its abstract > distance. A memory tier corresponds to a range of abstract distance. This allows > for classifying memory devices with a specific performance range into a memory > tier. > > By default, all memory nodes are assigned to the default tier with > abstract distance 512. > > A device driver can move its memory nodes from the default tier. For example, > PMEM can move its memory nodes below the default tier, whereas GPU can move its > memory nodes above the default tier. > > The kernel initialization code makes the decision on which exact tier a memory > node should be assigned to based on the requests from the device drivers as well > as the memory device hardware information provided by the firmware. > > Hot-adding/removing CPUs doesn't affect memory tier hierarchy. > > Changes from v14 > * Add Reviewed-by: > * Address review feedback w.r.t default adistance value > > Changes from v13 > * Address review feedback. > * Add path dropping memtier from struct memory_dev_type > > Changes from v12 > * Fix kernel crash on module unload > * Address review feedback. > * Add node_random patch to this series based on review feedback > > Changes from v11: > * smaller abstract distance imply faster(higher) memory tier. > > Changes from v10: > * rename performance level to abstract distance > * Thanks to all the good feedback from Huang, Ying . > Updated the patchset to cover most of the review feedback. > > Changes from v9: > * Use performance level for initializing memory tiers. > > Changes from v8: > * Drop the sysfs interface patches and related documentation changes. > > Changes from v7: > * Fix kernel crash with demotion. > * Improve documentation. > > Changes from v6: > * Drop the usage of rank. > * Address other review feedback. > > Changes from v5: > * Remove patch supporting N_MEMORY node removal from memory tiers. memory tiers > are going to be used for features other than demotion. Hence keep all N_MEMORY > nodes in memory tiers irrespective of whether they want to participate in promotion or demotion. > * Add NODE_DATA->memtier > * Rearrage patches to add sysfs files later. > * Add support to create memory tiers from userspace. > * Address other review feedback. > > > Changes from v4: > * Address review feedback. > * Reverse the meaning of "rank": higher rank value means higher tier. > * Add "/sys/devices/system/memtier/default_tier". > * Add node_is_toptier > > v4: > Add support for explicit memory tiers and ranks. > > v3: > - Modify patch 1 subject to make it more specific > - Remove /sys/kernel/mm/numa/demotion_targets interface, use > /sys/devices/system/node/demotion_targets instead and make > it writable to override node_states[N_DEMOTION_TARGETS]. > - Add support to view per node demotion targets via sysfs > > v2: > In v1, only 1st patch of this patch series was sent, which was > implemented to avoid some of the limitations on the demotion > target sharing, however for certain numa topology, the demotion > targets found by that patch was not most optimal, so 1st patch > in this series is modified according to suggestions from Huang > and Baolin. Different examples of demotion list comparasion > between existing implementation and changed implementation can > be found in the commit message of 1st patch. > > > Aneesh Kumar K.V (9): > mm/demotion: Add support for explicit memory tiers > mm/demotion: Move memory demotion related code > mm/demotion: Add hotplug callbacks to handle new numa node onlined > mm/demotion/dax/kmem: Set node's abstract distance to > MEMTIER_DEFAULT_DAX_ADISTANCE > mm/demotion: Build demotion targets based on explicit memory tiers > mm/demotion: Add pg_data_t member to track node memory tier details > mm/demotion: Drop memtier from memtype > mm/demotion: Update node_is_toptier to work with memory tiers > lib/nodemask: Optimize node_random for nodemask with single NUMA node > > Jagdish Gediya (1): > mm/demotion: Demote pages according to allocation fallback order > > drivers/dax/kmem.c | 42 ++- > include/linux/memory-tiers.h | 102 ++++++ > include/linux/migrate.h | 15 - > include/linux/mmzone.h | 3 + > include/linux/node.h | 5 - > include/linux/nodemask.h | 15 +- > mm/Makefile | 1 + > mm/huge_memory.c | 1 + > mm/memory-tiers.c | 645 +++++++++++++++++++++++++++++++++++ > mm/migrate.c | 453 +----------------------- > mm/mprotect.c | 1 + > mm/vmscan.c | 59 +++- > mm/vmstat.c | 4 - > 13 files changed, 849 insertions(+), 497 deletions(-) > create mode 100644 include/linux/memory-tiers.h > create mode 100644 mm/memory-tiers.c > > -- > 2.37.2 >