From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id 560D97F37 for ; Mon, 23 Nov 2015 17:21:53 -0600 (CST) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay2.corp.sgi.com (Postfix) with ESMTP id 47BC730405F for ; Mon, 23 Nov 2015 15:21:50 -0800 (PST) Received: from ipmail07.adl2.internode.on.net (ipmail07.adl2.internode.on.net [150.101.137.131]) by cuda.sgi.com with ESMTP id ZEMXkJdo6xVWep6m for ; Mon, 23 Nov 2015 15:21:47 -0800 (PST) Date: Tue, 24 Nov 2015 10:20:52 +1100 From: Dave Chinner Subject: Re: Does XFS support cgroup writeback limiting? Message-ID: <20151123232052.GI26718@dastard> References: <5652F311.7000406@5t9.de> <20151123202619.GE26718@dastard> <56538E6A.6030203@5t9.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <56538E6A.6030203@5t9.de> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Lutz Vieweg Cc: xfs@oss.sgi.com On Mon, Nov 23, 2015 at 11:08:42PM +0100, Lutz Vieweg wrote: > On 11/23/2015 09:26 PM, Dave Chinner wrote: > >On Mon, Nov 23, 2015 at 12:05:53PM +0100, Lutz Vieweg wrote: > >>in June 2015 the article https://lwn.net/Articles/648292/ mentioned > >>upcoming support for limiting the quantity of buffered writes > >>using control groups. > >> > >>Back then, only ext4 was said to support that feature, with other > >>filesystems requiring some minor changes to do the same. > > > >Yes, changing the kernel code to support this functionality is about > >3 lines of code. > > Oh, I didn't expect it to be such a small change :-) > > >.... I haven't added support to XFS because I have no way of > >verifying the functionality works and that it continues to work as > >it is intended. i.e. we have no regression test coverage for cgroup > >aware writeback and until someone writes a set of regression tests > >that validate it's functionality works correctly it will remain this > >way. > > > >Writing code is trivial. Validating the code actually works as > >intended and doesn't silently get broken in the future is the > >hard part.... > > Understood, would you anyway be willing to publish such a > three-line-patch (outside of official releases) for those > daredevils (like me :-)) who'd be willing to give it a try? Just make the same mods to XFS as the ext4 patch here: http://www.spinics.net/lists/kernel/msg2014816.html > After all, this functionality is the last piece of the > "isolation"-puzzle that is missing from Linux to actually > allow fencing off virtual machines or containers from DOSing > each other by using up all I/O bandwidth... Yes, I know, but no-one seems to care enough about it to provide regression tests for it. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs