From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757798AbdKOMX5 (ORCPT ); Wed, 15 Nov 2017 07:23:57 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:44550 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752279AbdKOMXt (ORCPT ); Wed, 15 Nov 2017 07:23:49 -0500 Date: Wed, 15 Nov 2017 12:23:14 +0000 From: Roman Gushchin To: Michal Hocko CC: , Johannes Weiner , Vladimir Davydov , Andrew Morton , Tejun Heo , Mike Kravetz , Dave Hansen , , , Subject: Re: [PATCH] memcg: hugetlbfs basic usage accounting Message-ID: <20171115122306.GA16468@castle> References: <20171114172429.8916-1-guro@fb.com> <20171115083504.nwczf5xq6posy3bw@dhcp22.suse.cz> <20171115111803.GA28352@castle> <20171115114223.ykyfrnxvvzhiglfd@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20171115114223.ykyfrnxvvzhiglfd@dhcp22.suse.cz> User-Agent: Mutt/1.9.1 (2017-09-22) X-Originating-IP: [2620:10d:c092:180::1:c198] X-ClientProxiedBy: DB6P190CA0012.EURP190.PROD.OUTLOOK.COM (2603:10a6:6:2f::25) To CO1PR15MB1078.namprd15.prod.outlook.com (2a01:111:e400:7b66::8) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 7b3346ef-1eef-453c-fa26-08d52c23ad1b X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(4534020)(4602075)(4627115)(201703031133081)(201702281549075)(2017052603258);SRVR:CO1PR15MB1078; 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Is there any fundamental reason why > > > hugetlb controller is not v2 compatible? > > > > I really don't know if the hugetlb controller has enough users to deserve > > full support in v2 interface: adding knobs like memory.hugetlb.current, > > memory.hugetlb.min, memory.hugetlb.high, memory.hugetlb.max, etc. > > > > I'd be rather conservative here and avoid adding a lot to the interface > > without clear demand. Also, hugetlb pages are really special, and it's > > at least not obvious how, say, memory.high should work for it. > > But you clearly want the hugetlb accoutning and that is what hugetlb > controller is for. You might not be interested in the limit enforcement > but that is not strictly required. So my question remains. Why don't we > reuse an existing infrastructure and add a new which might confuse users > in an extreme case? Hm, but to use a small part of hugetlb controller infrastructure I would have to add a whole set of cgroup v2 controls. And control knobs (like memory.hugetlb.current) are much more obligatory than an entry in memory.stat, where we have some internal stats as well. So, I don't really know why confusion should come from in this case? It would be confusing, if we'd add hugetlb stats to the memory.current, so that it could be larger then memory.max. But as separate entry in memory.stat it should not confuse anyone, at least not more than the existing state of things, when hugetlb pages are a black hole. > > Please note that I am not saying your patch is wrong, I just do not see > why we should handle hugetlb pages 2 different ways to achieve a common > infrastructure. This is perfectly fine, and I do understand it. My point is that it's a cheap way to solve a real problem, which is also not binding us too much. Thanks!