https://bugzilla.kernel.org/show_bug.cgi?id=111921 may be of interest.
** Bug watch added: Linux Kernel Bug Tracker #111921 http://bugzilla.kernel.org/show_bug.cgi?id=111921 -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1536837 Title: Severe performance regression in Infiniband or IPoIB Status in linux package in Ubuntu: Incomplete Bug description: When upgrading to the latest 4.4 test kernel from mainline development, all IPoIB links showed a severe performance regression as compared with kernel 4.2. The bandwidth of each link dropped from around 3Gbps to around 3Mbps (3 orders of magnitude worse!); reverting to the 4.2 kernel immediately fixed this problem. The 4.3 kernel from Debian does not appear to suffer from this regression. The regression shows up on both IB ports of the Mellanox MT25208 controller. Other hardware has not been tested. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1536837/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
