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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE4B9C433EF for ; Thu, 12 May 2022 08:15:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351356AbiELIPT (ORCPT ); Thu, 12 May 2022 04:15:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238788AbiELIPQ (ORCPT ); Thu, 12 May 2022 04:15:16 -0400 Received: from mail-vs1-xe33.google.com (mail-vs1-xe33.google.com [IPv6:2607:f8b0:4864:20::e33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C9A55DBE5 for ; Thu, 12 May 2022 01:15:15 -0700 (PDT) Received: by mail-vs1-xe33.google.com with SMTP id z144so4352799vsz.13 for ; Thu, 12 May 2022 01:15:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=/kBci1W7ElbeGBHJ1hfhdl2XSbKvaGs7BroRgBbCQZo=; b=Cd4mlvT0wAHMlu843hQ2fzttNtiSDYFX+5ywjAiSsqWPmY57usrCShYlfN7Mbvcdmt +qeiNNzs5TbqihtFVYSQa4/oqgA+cdzNuCbcBTKqHXQiZB3VBzDEb0zyW5IP2hU8iUII irzbNiNQIkxIRIKpkjbR1gPvZhqcX2dyMBKtxVQhObyyR0c36cSht3LXMNWgqNsc5FWU UqNji9+7nuSdOIs5zagiM3WPA45ZOYxSUgBTQpYpfkI0xL0AGy71tTQX8WUQLexeLZaD 0Lsf9FtQcdudxyDWy/DDjg6H1OW0zJUmFJM4Wqw1qVDDA/R/bVlHQpm5EefWU6EGXkxI 0B6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=/kBci1W7ElbeGBHJ1hfhdl2XSbKvaGs7BroRgBbCQZo=; b=KLQqunuxrh0cDPqrFZ6n9fp6NWDfEmKudeUKAbGw4Q8k6P4Q7+tctwd90J/vPPRe7s s6vLHwGG6HTOF3uNF/SZZjpO5gW8kY6uzS3YL4yeVlbTkXrHY5kcwRSpRjZvFTPmuzvp ieog6cPLoUyAp9kxsr9WvUWQ7Me3Vpxeu4Ike36Q4OxsZFadga1t0MndKteuSOXfguLF +9EgCbApUMzvM2aj6IdSwbJbqvkl7Ew62QbZAAGe67gGTMkdqNtje7au2xZfWdpvQwIl 9PmV6dr/eNex6ugFjPTOg/1BJZWBA/tpmHTx2KKAcKokQqSld1r9NByaQnS8zyMJ1/ee w3nQ== X-Gm-Message-State: AOAM532l0TudK5dBIEaISX376vA3BrLJs+lF7VYdMCsN+iMBxsTQ2/Vc WlPvbdPw4QnJ628DyxPG0zP4Bom/iShgHipyke7erg== X-Google-Smtp-Source: ABdhPJzPzd2BDtAqiKjsVfbVTVxWDPHGxJVJh1u7ZlaNKMR+DgMc23NLeblIidUa31ZpEUGf+a+M1cWxPuob2yA73Ck= X-Received: by 2002:a67:f343:0:b0:32c:c4b7:e238 with SMTP id p3-20020a67f343000000b0032cc4b7e238mr14522518vsm.77.1652343314311; Thu, 12 May 2022 01:15:14 -0700 (PDT) MIME-Version: 1.0 References: <56b41ce6922ed5f640d9bd46a603fa27576532a9.camel@intel.com> <87y1z7jj85.fsf@linux.ibm.com> In-Reply-To: <87y1z7jj85.fsf@linux.ibm.com> From: Wei Xu Date: Thu, 12 May 2022 01:15:03 -0700 Message-ID: Subject: Re: RFC: Memory Tiering Kernel Interfaces (v2) To: "Aneesh Kumar K.V" Cc: "ying.huang@intel.com" , Andrew Morton , Greg Thelen , Yang Shi , Linux Kernel Mailing List , Jagdish Gediya , Michal Hocko , Tim C Chen , Dave Hansen , Alistair Popple , Baolin Wang , Feng Tang , Jonathan Cameron , Davidlohr Bueso , Dan Williams , David Rientjes , Linux MM , Brice Goglin , Hesham Almatary Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 12, 2022 at 12:36 AM Aneesh Kumar K.V wrote: > > Wei Xu writes: > > > On Thu, May 12, 2022 at 12:12 AM Aneesh Kumar K V > > wrote: > >> > >> On 5/12/22 12:33 PM, ying.huang@intel.com wrote: > >> > On Wed, 2022-05-11 at 23:22 -0700, Wei Xu wrote: > >> >> Sysfs Interfaces > >> >> ================ > >> >> > >> >> * /sys/devices/system/memtier/memtierN/nodelist > >> >> > >> >> where N = 0, 1, 2 (the kernel supports only 3 tiers for now). > >> >> > >> >> Format: node_list > >> >> > >> >> Read-only. When read, list the memory nodes in the specified tier. > >> >> > >> >> Tier 0 is the highest tier, while tier 2 is the lowest tier. > >> >> > >> >> The absolute value of a tier id number has no specific meaning. > >> >> What matters is the relative order of the tier id numbers. > >> >> > >> >> When a memory tier has no nodes, the kernel can hide its memtier > >> >> sysfs files. > >> >> > >> >> * /sys/devices/system/node/nodeN/memtier > >> >> > >> >> where N = 0, 1, ... > >> >> > >> >> Format: int or empty > >> >> > >> >> When read, list the memory tier that the node belongs to. Its value > >> >> is empty for a CPU-only NUMA node. > >> >> > >> >> When written, the kernel moves the node into the specified memory > >> >> tier if the move is allowed. The tier assignment of all other nodes > >> >> are not affected. > >> >> > >> >> Initially, we can make this interface read-only. > >> > > >> > It seems that "/sys/devices/system/node/nodeN/memtier" has all > >> > information we needed. Do we really need > >> > "/sys/devices/system/memtier/memtierN/nodelist"? > >> > > >> > That can be gotten via a simple shell command line, > >> > > >> > $ grep . /sys/devices/system/node/nodeN/memtier | sort -n -k 2 -t ':' > >> > > >> > >> It will be really useful to fetch the memory tier node list in an easy > >> fashion rather than reading multiple sysfs directories. If we don't have > >> other attributes for memorytier, we could keep > >> "/sys/devices/system/memtier/memtierN" a NUMA node list there by > >> avoiding /sys/devices/system/memtier/memtierN/nodelist > >> > >> -aneesh > > > > It is harder to implement memtierN as just a file and doesn't follow > > the existing sysfs pattern, either. Besides, it is extensible to have > > memtierN as a directory. > > diff --git a/drivers/base/node.c b/drivers/base/node.c > index 6248326f944d..251f38ec3816 100644 > --- a/drivers/base/node.c > +++ b/drivers/base/node.c > @@ -1097,12 +1097,49 @@ static struct attribute *node_state_attrs[] = { > NULL > }; > > +#define MAX_TIER 3 > +nodemask_t memory_tier[MAX_TIER]; > + > +#define _TIER_ATTR_RO(name, tier_index) \ > + { __ATTR(name, 0444, show_tier, NULL), tier_index, NULL } > + > +struct memory_tier_attr { > + struct device_attribute attr; > + int tier_index; > + int (*write)(nodemask_t nodes); > +}; > + > +static ssize_t show_tier(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct memory_tier_attr *mt = container_of(attr, struct memory_tier_attr, attr); > + > + return sysfs_emit(buf, "%*pbl\n", > + nodemask_pr_args(&memory_tier[mt->tier_index])); > +} > + > static const struct attribute_group memory_root_attr_group = { > .attrs = node_state_attrs, > }; > > + > +#define TOP_TIER 0 > +static struct memory_tier_attr memory_tiers[] = { > + [0] = _TIER_ATTR_RO(memory_top_tier, TOP_TIER), > +}; > + > +static struct attribute *memory_tier_attrs[] = { > + &memory_tiers[0].attr.attr, > + NULL > +}; > + > +static const struct attribute_group memory_tier_attr_group = { > + .attrs = memory_tier_attrs, > +}; > + > static const struct attribute_group *cpu_root_attr_groups[] = { > &memory_root_attr_group, > + &memory_tier_attr_group, > NULL, > }; > > > As long as we have the ability to see the nodelist, I am good with the > proposal. > > -aneesh I am OK with moving back the memory tier nodelist into node/. When there are more memory tier attributes needed, we can then create the memory tier subtree and replace the tier nodelist in node/ with symlinks. So the revised sysfs interfaces are: * /sys/devices/system/node/memory_tierN (read-only) where N = 0, 1, 2 Format: node_list * /sys/devices/system/node/nodeN/memory_tier (read/write) where N = 0, 1, ... Format: int or empty