From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755920AbbFOSX6 (ORCPT ); Mon, 15 Jun 2015 14:23:58 -0400 Received: from mail-yk0-f174.google.com ([209.85.160.174]:33849 "EHLO mail-yk0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754088AbbFOSXt (ORCPT ); Mon, 15 Jun 2015 14:23:49 -0400 Date: Mon, 15 Jun 2015 14:23:45 -0400 From: Tejun Heo To: Vivek Goyal Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, lizefan@huawei.com, cgroups@vger.kernel.org Subject: Re: [PATCH 3/3] writeback, blkio: add documentation for cgroup writeback support Message-ID: <20150615182345.GB18517@mtj.duckdns.org> References: <1434146254-26220-1-git-send-email-tj@kernel.org> <1434146254-26220-4-git-send-email-tj@kernel.org> <20150615172823.GA5783@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150615172823.GA5783@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hey, Vivek. On Mon, Jun 15, 2015 at 01:28:23PM -0400, Vivek Goyal wrote: > IIRC, I had run into the issues with two fsync running into two cgroups. > One cgroup was of really small limit and other was unlimited. At that > point of time I think conclusion was that multiple transactions could > not make progress at the same time. So slower cgroup had blocked unlimited > cgroup process from opening a transaction (as IO from slower group was > stuck inside throttling later). > > For some reason, in my limited testing I have not noticed it with your > branch. May be things have changed since or I am just hazy on details. > I will do some more testing. On ext2, there's nothing interlocking each other. My understanding of ext4 is pretty limited but as long as the journal head doesn't overwrap and gets bloked on the slow one, it should be fine, so for most use cases, this shouldn't be a problem. Thanks. -- tejun