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 4B85DC433F5 for ; Mon, 16 May 2022 01:57:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239234AbiEPB51 (ORCPT ); Sun, 15 May 2022 21:57:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58848 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236803AbiEPB5V (ORCPT ); Sun, 15 May 2022 21:57:21 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B77F7120B2 for ; Sun, 15 May 2022 18:57:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1652666239; x=1684202239; h=message-id:subject:from:to:cc:date:in-reply-to: references:mime-version:content-transfer-encoding; bh=5sJgBSyY05b4qS9qR14JupIuhy3CGzHPfdFfFtG7b+U=; b=CjmMVYP/HjTKtbTnNGiT+ii5lBuUAevk4HkEZHK5z94wGX4OsLx8pRjg rHpYbgHqUR/6Wjiq3beSf0FrnZxUidB/PNneQ6tWyI6tWmhSBHHsHQjmj Uu2hMxEpEej6q1Xi0fydfci92UJBgVEXnyw/N1JfEnaVPrrXqEn5s0xEh lBx7XdM/gLOYcaBbkf1eOR4wWI0isnV2sx14kZ9piofBVzcH+LM+O22Wk Dam2KJ+oP0G/XebaGM/ntLXm06A8fOQjROYV5pvlKT5FMbbPSf7k3kY41 sC7/IqRtdzmDq4vxHWiyjwDAn5Z98glesvsWfEHkpgQnP/c0v7wwGTjMA A==; X-IronPort-AV: E=McAfee;i="6400,9594,10348"; a="270658125" X-IronPort-AV: E=Sophos;i="5.91,229,1647327600"; d="scan'208";a="270658125" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 May 2022 18:57:17 -0700 X-IronPort-AV: E=Sophos;i="5.91,229,1647327600"; d="scan'208";a="568088155" Received: from rmo-mobl1.ccr.corp.intel.com ([10.254.215.134]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 May 2022 18:57:12 -0700 Message-ID: <83b2229ce198d446ace6112b39ceaa34c0864b41.camel@intel.com> Subject: Re: RFC: Memory Tiering Kernel Interfaces (v2) From: "ying.huang@intel.com" To: Wei Xu Cc: "Aneesh Kumar K.V" , 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 Date: Mon, 16 May 2022 09:57:10 +0800 In-Reply-To: References: <56b41ce6922ed5f640d9bd46a603fa27576532a9.camel@intel.com> <87y1z7jj85.fsf@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.3-1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2022-05-13 at 00:00 -0700, Wei Xu wrote: > On Thu, May 12, 2022 at 7:53 PM ying.huang@intel.com > wrote: > > > > On Thu, 2022-05-12 at 16:37 +0800, ying.huang@intel.com wrote: > > > On Thu, 2022-05-12 at 01:15 -0700, Wei Xu wrote: > > > > 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. > > > > > > What attributes do you imagine that we may put in memory_tierX/ sysfs > > > directory? If we have good candidates in mind, we may just do that. > > > What I can imagine now is "demote", like "memory_reclaim" in nodeX/ or > > > node/ directory you proposed before. Is it necessary to show something > > > like "meminfo", "vmstat" there? > > > > My words may be confusing, so let me say it in another way. > > I can understand. :) > > > Just for brainstorm, if we have > > > >   /sys/devices/system/memtier/memtierN/ > > > > What can we put in it in addition to "nodelist" or links to the nodes? > > For example, > > > >   /sys/devices/system/memtier/memtierN/demote > > > > When write a page number to it, the specified number of pages will be > > demoted from memtierN to memtierN+1, like the > > /sys/devices/system/node/memory_reclaim interface you proposed before. > > "demote" might be fine to add there. Just to clarify, we (Google) > currently don't yet have the need for an interface to do system-wide > demotion from one tier to another. What we need is memory.demote > (similar to memory.reclaim) for memory cgroup based demotions. > > Other things that might be added include tier-specific properties > (e.g. expected latency and bandwidth when available) and tier-specific > stats. > > Under /sys/devices/system/memtier/, we may add global properties about > memory tiers, e.g. max number of tiers, min/max tier ids (which might > be useful if we hide unpopulated memory tiers). > > > Or, is it necessary to add > > > >   /sys/devices/system/memtier/memtierN/meminfo > >   /sys/devices/system/memtier/memtierN/vmstat > > The userspace can aggregate such data from node/nodeN/{meminfo, > vmstat} based on the memory tier nodelist. But I am not against adding > these files to memtierN/ for user convenience. > > > I don't mean to propose these. Just want to know whether there's > > requirement for these kind of stuff? And what else may be required. > > This sounds good. I think a memtier directory may eventually become a > necessity, though I don't feel too strongly about adding it right now. If a memtier directory may eventually become a necessity and we really want convenient nodelist somewhere, I'm OK to add the memtier directory now. Best Regards, Huang, Ying > > Best Regards, > > Huang, Ying > > > > > > > > > > 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 > > > > > > > > >