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 7F0567F37 for ; Mon, 23 Nov 2015 16:08:06 -0600 (CST) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay2.corp.sgi.com (Postfix) with ESMTP id 53BDA30405F for ; Mon, 23 Nov 2015 14:08:03 -0800 (PST) Received: from app1b.xlhost.de (mailout173.xlhost.de [84.200.252.173]) by cuda.sgi.com with ESMTP id sDFdRGxMEFUd4FPP for ; Mon, 23 Nov 2015 14:08:01 -0800 (PST) Message-ID: <56538E6A.6030203@5t9.de> Date: Mon, 23 Nov 2015 23:08:42 +0100 From: Lutz Vieweg MIME-Version: 1.0 Subject: Re: Does XFS support cgroup writeback limiting? References: <5652F311.7000406@5t9.de> <20151123202619.GE26718@dastard> In-Reply-To: <20151123202619.GE26718@dastard> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Dave Chinner Cc: xfs@oss.sgi.com 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? 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... Regards, Lutz Vieweg _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs