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 CEE2AC433EF for ; Thu, 12 May 2022 21:13:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 005BA6B0073; Thu, 12 May 2022 17:13:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EF5BF6B0075; Thu, 12 May 2022 17:13:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D6FBD6B0078; Thu, 12 May 2022 17:13:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id C6A6B6B0073 for ; Thu, 12 May 2022 17:13:01 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 9863820CA5 for ; Thu, 12 May 2022 21:13:01 +0000 (UTC) X-FDA: 79458340962.28.066DCE7 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by imf09.hostedemail.com (Postfix) with ESMTP id F30B0140099 for ; Thu, 12 May 2022 21:12:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1652389980; x=1683925980; h=message-id:subject:from:to:cc:date:in-reply-to: references:mime-version:content-transfer-encoding; bh=xEM/Zk24Z91Nu9Mfk4uyW9jIi/U1i8D6/+PSEsiXcGk=; b=FKay9Vg46LjLlKInA90Az9isQ5eDSWtf0dvADKxGM6RUX8Gm0Q4RujRT X/HgJLeJDT0sQhwNW2vAYK3KN71AQdkkfPtlXhc79hOjfzwflFg2TRQYs JuNI9LPYzLi6LhsBap6PvFwJdk42SyeZR0RBvBqqH34cozCovw7Mguak8 JxfW2OEeyZUV0vDQ4yxMiKsOZuQ87VaJHSfyqqesP8c43gYfWs+VyfWdd 8OkXfVRc/MbMpPwLxfyzLeG3ZfmWIVfklR/7LX2oByRRH074ArR9qRnZY Z2sWKSAzFJOvfSCSgt54u+ZtkAdYG2zJLGyxL2MEgP/vPj2ep+4afb3gw g==; X-IronPort-AV: E=McAfee;i="6400,9594,10345"; a="270073261" X-IronPort-AV: E=Sophos;i="5.91,221,1647327600"; d="scan'208";a="270073261" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 May 2022 14:12:53 -0700 X-IronPort-AV: E=Sophos;i="5.91,221,1647327600"; d="scan'208";a="594875294" Received: from schen9-mobl.amr.corp.intel.com ([10.209.114.19]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 May 2022 14:12:51 -0700 Message-ID: <333438929a8680317bdae02da921d1e50fb9b0b3.camel@linux.intel.com> Subject: Re: RFC: Memory Tiering Kernel Interfaces (v2) From: Tim Chen To: Wei Xu , "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 Date: Thu, 12 May 2022 14:12:51 -0700 In-Reply-To: References: <56b41ce6922ed5f640d9bd46a603fa27576532a9.camel@intel.com> <87y1z7jj85.fsf@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Stat-Signature: fkemp1ewkupcyk9ryznqbgfnzs6g8w6u Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=FKay9Vg4; spf=none (imf09.hostedemail.com: domain of tim.c.chen@linux.intel.com has no SPF policy when checking 134.134.136.65) smtp.mailfrom=tim.c.chen@linux.intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: F30B0140099 X-HE-Tag: 1652389971-512707 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: On Thu, 2022-05-12 at 01:15 -0700, Wei Xu wrote: > > 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 This looks good to me. Just wonder if having just 1 tier lower than DRAM is sufficient. We could have wide performance range for such secondary memories and is one tier sufficient for them? Tim