From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCHv12 1/3] rdmacg: Added rdma cgroup controller Date: Thu, 1 Sep 2016 10:44:06 +0200 Message-ID: <20160901084406.GA4115@lst.de> References: <1472632647-1525-1-git-send-email-pandit.parav@gmail.com> <1472632647-1525-2-git-send-email-pandit.parav@gmail.com> <61101e8b-5776-c0bc-b3ea-d8b984eebabf@mellanox.com> <20160831211618.GA12660@htj.duckdns.org> <9b6a346d-af4c-1e5f-0144-f68fb8e46c27@mellanox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <9b6a346d-af4c-1e5f-0144-f68fb8e46c27@mellanox.com> Sender: linux-kernel-owner@vger.kernel.org To: Matan Barak Cc: Tejun Heo , Parav Pandit , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, lizefan@huawei.com, hannes@cmpxchg.org, dledford@redhat.com, hch@lst.de, liranl@mellanox.com, sean.hefty@intel.com, jgunthorpe@obsidianresearch.com, haggaie@mellanox.com, corbet@lwn.net, james.l.morris@oracle.com, serge@hallyn.com, ogerlitz@mellanox.com, akpm@linux-foundation.org, linux-security-module@vger.kernel.org List-Id: linux-rdma@vger.kernel.org On Thu, Sep 01, 2016 at 10:25:40AM +0300, Matan Barak wrote: > Well, if I recall, the reason doing so last time was in order to allow > flexible updating of ib_core independently, which is obviously not a good > reason (to say the least). > > Since the new ABI will probably define new object types (all recent > proposals go this way), the current approach could lead to either trying to > map new objects to existing cgroup resource types, which could lead to some > weird non 1:1 mapping, or having a split definitions - such that each > driver will declare its objects both in the cgroups mechanism and in its > driver dispatch table. > Even worse than that, drivers could simply ignore the cgroups support while > implementing their own resource types and get a very broken containers > support. Sorry guys, but arbitrary extensibility for something not finished is the worst idea ever. We have two options here: a) delay cgroups support until the grand rewrite is done b) add it now and deal with the consequences later That being said, adding random non-Verbs hardwasre to the RDMA core is the second worst idea ever. Guess I need to catch up with the discussion and start using the flame thrower.