From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hal Rosenstock Subject: Re: tune ib stack Date: Tue, 09 Apr 2013 10:23:26 -0400 Message-ID: <5164245E.2030208@dev.mellanox.co.il> References: <51640E72.3010202@dev.mellanox.co.il> <516414BD.4020407@profitbricks.com> <516418F4.4040908@dev.mellanox.co.il> <51641E0D.2050009@profitbricks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51641E0D.2050009-EIkl63zCoXaH+58JC4qpiA@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sebastian Riemer Cc: Vasiliy Tolstov , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org On 4/9/2013 9:56 AM, Sebastian Riemer wrote: > On 09.04.2013 15:34, Hal Rosenstock wrote: >> On 4/9/2013 9:16 AM, Sebastian Riemer wrote: >>> On 09.04.2013 14:49, Hal Rosenstock wrote: >>>> On 4/9/2013 7:12 AM, Vasiliy Tolstov wrote: >>>>> Hello. I have some servers, with mellanox ConnectX-3 and have some questions: >>>>> Why max_mtu differs with active_mtu? >>>> >>>> What does peer port say for max MTU ? >>>> >>>>> How can i set active mtu? >>>> >>>> SM sets active MTU to min of peer ports max MTUs. >>> >>> So with "peer port max MTU" do you mean this file?: >>> >>> /sys/class/infiniband/mlx4_0/device/mlx4_port1_mtu >> >> I meant NeighborMTU from PortInfo as active MTU and MTUCap there is >> supported MTU. > > So these values are exactly the same as in "ibv_devinfo" and can be set > in /sys/class/infiniband/mlx4_0/device/mlx4_port1_mtu. > > I've found the PortInfo with the command > "smpquery portinfo -C mlx4_0 3 1" > where I'm using the first HCA to contact the SM. I tell the SM the > destination LID ('3' here in my case) and the destination port ('1'). > > Is there another method to set the max MTU? That doesn't set max MTU (MTUCap) but merely reads it (for that port). > I know that switches can also set the max MTU for their switch ports > where most of them use 2048 as default. You would need to contact your CA and/or switch vendor(s) (see below). > How to change these switch port MTUs for unmanaged switches? > > On managed switches this can be done over the web front-end. Yes. MTUCap is RO in terms of the SM so there are only "out of band" mechanisms to change this which are vendor specific like a web front end. -- Hal > Cheers, > Sebastian > -- 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