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 333C1C433EF for ; Thu, 12 May 2022 21:12:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358639AbiELVM4 (ORCPT ); Thu, 12 May 2022 17:12:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235641AbiELVMx (ORCPT ); Thu, 12 May 2022 17:12:53 -0400 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9E9EF5DE69 for ; Thu, 12 May 2022 14:12:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1652389972; x=1683925972; h=message-id:subject:from:to:cc:date:in-reply-to: references:mime-version:content-transfer-encoding; bh=xEM/Zk24Z91Nu9Mfk4uyW9jIi/U1i8D6/+PSEsiXcGk=; b=ErMB3au89ofzuAyfLP6VPBcajg375jctOaF0wm8Kk/arRJ6GP1DuhWrn Mgn40yKJ53Y90QwaY9PHfyRJ4c/zPxRKSka6g1+mGl8SFVMxdnkp/Pobu reP1P4w1x8x6PQ5g/39WUmpovlK8TOlGjB4Ldu+5pt1oDre1k4CI1iJuM bNgemD2N5BUXiyu6VGFjCbwyfn5eeUW3UUlJkHbWZimJjrizNl33xS1Hd ihRMiUc2bBW4wp8ohWHYchlF4PG/37up8sd/zP0Bw71po5HXBxgU0bCSN 6IiEVpOa5ZZqeRIILfhRvnx4vZO+H/xwD0gCvD3yBiiZUUF/lSmOW1wux w==; X-IronPort-AV: E=McAfee;i="6400,9594,10345"; a="267729186" X-IronPort-AV: E=Sophos;i="5.91,221,1647327600"; d="scan'208";a="267729186" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 May 2022 14:12:52 -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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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