From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f173.google.com ([209.85.216.173]:34607 "EHLO mail-qt0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755788AbcKWVLN (ORCPT ); Wed, 23 Nov 2016 16:11:13 -0500 Date: Wed, 23 Nov 2016 16:11:10 -0500 From: Tejun Heo To: Shaohua Li Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Kernel-team@fb.com, axboe@fb.com, vgoyal@redhat.com Subject: Re: [PATCH V4 02/15] blk-throttle: add .high interface Message-ID: <20161123211018.GA11306@mtj.duckdns.org> References: <239e20c62e028b570f48403faea1419c4d84f2bd.1479161136.git.shli@fb.com> <20161122200253.GA17534@htj.duckdns.org> <20161122230836.GA14628@shli-mbp.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20161122230836.GA14628@shli-mbp.local> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org Hello, On Tue, Nov 22, 2016 at 03:08:36PM -0800, Shaohua Li wrote: > Yep, the limit could be high or max. It's doable moving the restrictions on > input, but will increase trouble using the limits. If high is bigger than max, > can I set high to max? if not, I'd prefer to keep the restrictions. You can do that internally but userland should keep seeing what it configured. > > I haven't read the whole thing yet but this looks a bit suspicious. A > > css going offline indicates that the destruction of the css started. > > I don't get why that'd reset high limits. There can be a lot of async > > IOs after offline. > > Ok. We do want to reset the limits. Because if no cgroup has high limit, we > definitively should use max limit for all cgroups. The whole state machine > (switching between high and max limit) is meaningless in that case. > > Is pd_free_fn a good place to guarantee anyc IOs finish? Yeap. Thanks. -- tejun