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 D4897C433F5 for ; Tue, 3 May 2022 17:47:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240636AbiECRu6 (ORCPT ); Tue, 3 May 2022 13:50:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40748 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240621AbiECRu4 (ORCPT ); Tue, 3 May 2022 13:50:56 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FE1427B0E for ; Tue, 3 May 2022 10:47:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1651600042; x=1683136042; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=sxiHAHKs3kGHAX7nEqE25i1M6VS4EbzVzl9niPw4Uv4=; b=TCYXAwFjhAWnieAh5FBmN7OkM7sTqpS/kbwsv4/Zh8neiMsWhZUT9VHi 4kYO0FjWa7NmsPDs9/b3yIRH3GiitTGXFdY/bpEYPMMS3kxO1/7pZPd6J sJFsmWrU6NkbUsewPle5KrDr6hSATZvbZ9Is0wTcdEH3lF/tzvVu6Gv0o bQs6PR/ArRjo2vD1iXEXwXUI8Wpaic2qIS+RqbdvrrVwe49ZNWSyD2NmY Sud+kh7Lv4i+1rUD9+tqFfieTiaobaeuvNbz+o/f6xrUbjSaZY3Z5LnAJ McJrgtEKjBneRD6pxrwveUTqZdJ1AQGnYyeTHrcbQ92jVLGCJhYNGtx51 g==; X-IronPort-AV: E=McAfee;i="6400,9594,10336"; a="267136843" X-IronPort-AV: E=Sophos;i="5.91,195,1647327600"; d="scan'208";a="267136843" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 May 2022 10:47:02 -0700 X-IronPort-AV: E=Sophos;i="5.91,195,1647327600"; d="scan'208";a="536435108" Received: from prdidome-mobl.amr.corp.intel.com (HELO [10.212.51.158]) ([10.212.51.158]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 May 2022 10:47:01 -0700 Message-ID: Date: Tue, 3 May 2022 10:47:20 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: RFC: Memory Tiering Kernel Interfaces Content-Language: en-US To: Alistair Popple , Davidlohr Bueso Cc: Wei Xu , Andrew Morton , Dave Hansen , Huang Ying , Dan Williams , Yang Shi , Linux MM , Greg Thelen , "Aneesh Kumar K.V" , Jagdish Gediya , Linux Kernel Mailing List , Michal Hocko , Baolin Wang , Brice Goglin , Feng Tang , Jonathan.Cameron@huawei.com References: <20220501175813.tvytoosygtqlh3nn@offworld> <87o80eh65f.fsf@nvdebian.thelocal> From: Dave Hansen In-Reply-To: <87o80eh65f.fsf@nvdebian.thelocal> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/3/22 10:14, Alistair Popple wrote: > I would certainly be interested in figuring out how HW could provide some sort > of heatmap to identify which pages are hot and which processing unit is using > them. Currently for these systems users have to manually assign memory policy to > get any reasonable performance, both to disable NUMA balancing and make sure > memory is allocated on the right node. Autonuma-induced page faults are a total non-starter for lots of workloads, even ignoring GPUs. Basically anyone who is latency sensitive stays far, far away from autonuma. As for improving on page faults for data collection... *Can* hardware provide this information? Definitely. Have hardware vendors been motivated enough to add hardware to do this? Nope, not yet. Do you know anyone that works for any hardware companies? ;) Seriously, though. Folks at Intel _are_ thinking about this problem. I'm hoping we have hardware some day to help lend a hand. The more hardware vendors that do this, the more likely it is that we'll have good kernel code to consume data from the hardware.