From mboxrd@z Thu Jan 1 00:00:00 1970 From: "ira.weiny" Subject: Re: [RFC] libibverbs IB device hotplug support Date: Tue, 28 Feb 2017 19:10:24 -0500 Message-ID: <20170301001023.GA3001@phlsvsds.ph.intel.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alex Rosenbaum Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Yishai Hadas List-Id: linux-rdma@vger.kernel.org On Mon, Feb 27, 2017 at 06:08:41PM +0200, Alex Rosenbaum wrote: > Introduction > > -------------------------------------------------------------------------------- > > Hotplug [1] is the method in which new hardware becomes available in the system > > or is being removed from it. User space applications would like to continue > > operation while hardware is being changed in the system, without the need to > > restart the process, lose its current state and lose open sessions (at least on > > other available hardware). > > > > The problem > > -------------------------------------------------------------------------------- > > Today the IB device list is returned by ibv_get_device_list() from libibverbs. > > This IB device list is created by scanning of the /sys/class/infiniband_verbs > > [2]. The list is cached and never updated, no matter if there were hardware > > changes in the system. After the call it occurred to me that we may be missing a bigger picture with this discussion. In the past we have discussed in the past what exactly a "struct ib_device" is within the context of the kernel. Should we also consider "port hotplug"? For example what happens if a Mellanox port is unplugged from an IB port and plugged into an Ethernet port? Is that considered a "device" hot plug? What happens if this is a dual port device and only one of the 2 IB ports are changed? So many things like AH, Path Records, etc are tied to the "device" but really they should be tied to the port. To be clear I am not opposed to this change at this time. But I think we should consider shifting the model away from devices and toward ports as we continue. Ira -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html