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=-2.2 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 75638C433DF for ; Fri, 19 Jun 2020 20:42:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C12F2100A for ; Fri, 19 Jun 2020 20:42:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390741AbgFSUl5 (ORCPT ); Fri, 19 Jun 2020 16:41:57 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:29846 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388929AbgFSUl5 (ORCPT ); Fri, 19 Jun 2020 16:41:57 -0400 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 05JKVqrN159665; Fri, 19 Jun 2020 16:41:44 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 31rthajuyn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 19 Jun 2020 16:41:43 -0400 Received: from m0098419.ppops.net (m0098419.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 05JKVsWf159881; Fri, 19 Jun 2020 16:41:43 -0400 Received: from ppma02wdc.us.ibm.com (aa.5b.37a9.ip4.static.sl-reverse.com [169.55.91.170]) by mx0b-001b2d01.pphosted.com with ESMTP id 31rthajuyd-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 19 Jun 2020 16:41:43 -0400 Received: from pps.filterd (ppma02wdc.us.ibm.com [127.0.0.1]) by ppma02wdc.us.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 05JKdf0o025533; Fri, 19 Jun 2020 20:41:42 GMT Received: from b01cxnp22036.gho.pok.ibm.com (b01cxnp22036.gho.pok.ibm.com [9.57.198.26]) by ppma02wdc.us.ibm.com with ESMTP id 31rdtfga8a-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 19 Jun 2020 20:41:42 +0000 Received: from b01ledav002.gho.pok.ibm.com (b01ledav002.gho.pok.ibm.com [9.57.199.107]) by b01cxnp22036.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 05JKfgle14287410 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 19 Jun 2020 20:41:42 GMT Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 15134124052; Fri, 19 Jun 2020 20:41:42 +0000 (GMT) Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4FA7E124058; Fri, 19 Jun 2020 20:41:40 +0000 (GMT) Received: from [9.163.11.155] (unknown [9.163.11.155]) by b01ledav002.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 19 Jun 2020 20:41:40 +0000 (GMT) Subject: Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement To: Tejun Heo , Ian Kent Cc: 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> From: Rick Lindsley Message-ID: <16d9d5aa-a996-d41d-cbff-9a5937863893@linux.vnet.ibm.com> Date: Fri, 19 Jun 2020 13:41:39 -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: <20200619153833.GA5749@mtj.thefacebook.com> 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=2020-06-19_21:2020-06-19,2020-06-19 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 clxscore=1015 priorityscore=1501 adultscore=0 malwarescore=0 mlxscore=0 mlxlogscore=893 spamscore=0 impostorscore=0 suspectscore=0 bulkscore=0 cotscore=-2147483648 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006190141 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 6/19/20 8:38 AM, Tejun Heo wrote: > I don't have strong objections to the series but the rationales don't seem > particularly strong. It's solving a suspected problem but only half way. It > isn't clear whether this can be the long term solution for the problem > machine and whether it will benefit anyone else in a meaningful way either. I don't understand your statement about solving the problem halfway. Could you elaborate? > I think Greg already asked this but how are the 100,000+ memory objects > used? Is that justified in the first place? They are used for hotplugging and partitioning memory. The size of the segments (and thus the number of them) is dictated by the underlying hardware. Rick