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 X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F0C7C433E0 for ; Mon, 22 Jun 2020 21:22:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5766320732 for ; Mon, 22 Jun 2020 21:22:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730474AbgFVVWx (ORCPT ); Mon, 22 Jun 2020 17:22:53 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:39748 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730460AbgFVVWw (ORCPT ); Mon, 22 Jun 2020 17:22:52 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 05ML2xIt106480; Mon, 22 Jun 2020 17:22:38 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 31tysvg7v8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 22 Jun 2020 17:22:38 -0400 Received: from m0098393.ppops.net (m0098393.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 05ML4WE3112081; Mon, 22 Jun 2020 17:22:38 -0400 Received: from ppma01dal.us.ibm.com (83.d6.3fa9.ip4.static.sl-reverse.com [169.63.214.131]) by mx0a-001b2d01.pphosted.com with ESMTP id 31tysvg7uv-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 22 Jun 2020 17:22:38 -0400 Received: from pps.filterd (ppma01dal.us.ibm.com [127.0.0.1]) by ppma01dal.us.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 05MLFbdJ028588; Mon, 22 Jun 2020 21:22:37 GMT Received: from b03cxnp07028.gho.boulder.ibm.com (b03cxnp07028.gho.boulder.ibm.com [9.17.130.15]) by ppma01dal.us.ibm.com with ESMTP id 31sa38q828-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 22 Jun 2020 21:22:37 +0000 Received: from b03ledav003.gho.boulder.ibm.com (b03ledav003.gho.boulder.ibm.com [9.17.130.234]) by b03cxnp07028.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 05MLMZtg41353574 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 22 Jun 2020 21:22:36 GMT Received: from b03ledav003.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E265B6A047; Mon, 22 Jun 2020 21:22:35 +0000 (GMT) Received: from b03ledav003.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3CC7D6A051; Mon, 22 Jun 2020 21:22:35 +0000 (GMT) Received: from [9.211.67.55] (unknown [9.211.67.55]) by b03ledav003.gho.boulder.ibm.com (Postfix) with ESMTP; Mon, 22 Jun 2020 21:22:35 +0000 (GMT) Subject: Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement To: Tejun Heo Cc: Ian Kent , Greg Kroah-Hartman , Stephen Rothwell , Andrew Morton , Al Viro , David Howells , Miklos Szeredi , linux-fsdevel , Kernel Mailing List References: <159237905950.89469.6559073274338175600.stgit@mickey.themaw.net> <20200619153833.GA5749@mtj.thefacebook.com> <16d9d5aa-a996-d41d-cbff-9a5937863893@linux.vnet.ibm.com> <20200619222356.GA13061@mtj.duckdns.org> <20200622175343.GC13061@mtj.duckdns.org> From: Rick Lindsley Message-ID: <82b2379e-36d0-22c2-41eb-71571e992b37@linux.vnet.ibm.com> Date: Mon, 22 Jun 2020 14:22:34 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200622175343.GC13061@mtj.duckdns.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.687 definitions=2020-06-22_12:2020-06-22,2020-06-22 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 impostorscore=0 adultscore=0 spamscore=0 bulkscore=0 lowpriorityscore=0 clxscore=1015 phishscore=0 mlxscore=0 priorityscore=1501 malwarescore=0 cotscore=-2147483648 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006220137 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 6/22/20 10:53 AM, Tejun Heo wrote: > I don't know. The above highlights the absurdity of the approach itself to > me. You seem to be aware of it too in writing: 250,000 "devices". Just because it is absurd doesn't mean it wasn't built that way :) I agree, and I'm trying to influence the next hardware design. However, what's already out there is memory units that must be accessed in 256MB blocks. If you want to remove/add a GB, that's really 4 blocks of memory you're manipulating, to the hardware. Those blocks have to be registered and recognized by the kernel for that to work. Rick