From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:45784 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933981AbcKVXik (ORCPT ); Tue, 22 Nov 2016 18:38:40 -0500 Date: Tue, 22 Nov 2016 15:38:24 -0800 From: Shaohua Li To: Tejun Heo CC: , , , , Subject: Re: [PATCH V4 05/15] blk-throttle: add downgrade logic Message-ID: <20161122233824.GD14628@shli-mbp.local> References: <20161122212121.GC17534@htj.duckdns.org> <20161122214200.GE17534@htj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In-Reply-To: <20161122214200.GE17534@htj.duckdns.org> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Tue, Nov 22, 2016 at 04:42:00PM -0500, Tejun Heo wrote: > Hello, > > On Tue, Nov 22, 2016 at 04:21:21PM -0500, Tejun Heo wrote: > > 1. A cgroup and its high and max limits don't have much to do with > > other cgroups and their limits. I don't get how the choice between > > high and max limits can be a td-wide state. > > Ah, okay, this combines with idle cgroup detection to determine > whether the cgroups should be allowed to exceed high limits. It makes > more sense to me now. In that case, for the high/max limit range > issues, the enforced high/max limits can simply follow what's implied > by the configuration. e.g. if high=100 max=80, just behave as if both > high and max are 80. > > > 2. Comparing parent's and child's limits and saying that either can be > > ignored because one is higher than the other isn't correct. A > > parent's limit doesn't apply to each child separately. It has to > > be aggregated. e.g. you can ignore a parent's setting if the sum > > of all children's limits is smaller than the parent's but then > > again there could still be a lower limit higher up the tree, so > > they would still have to be examined. > > This part still seems weird tho. What am I misunderstanding? You are right, the checks are unncessary. I'll delete them. Thanks, Shaohua