On 01/14/2014 02:16 PM, Chaitanya Lala wrote: > Hello, > > I am trying to enable RSC/LRO on a VF (X540-AT2 based) which has been PCIe > passthrough'd to a Ubuntu VM (12.10) running latest ixgbevf. > The host machine is a dual socket E5-2600 machine with a bunch of dual > port X540 cards, running RHEL 6.2 Linux. > I am using ixgbe 3.15.1 on the host and have enabled SR-IOV. I cannot seem > to find a way to enable RSC/LRO in the guest OS on the VF (ethtool on the > guest ixgbevf does not let me do it). > On looking into ixgbe driver it seems that it disables RSC/LRO in > ixgbe_enable_sriov() function. My questions are - > > 1. It appears per X540 data sheet that enabling RSC on a VF should be a > supported option. IIUC this is a driver limitation. Am I correct ? > 2. If this is indeed a driver limitation then, I'd request if you could > point me to a driver patch or another way to overcome this (I am willing > to code up a patch if someone can point me to the solution.) > > Highly appreciate your help! > > Thanks, > Chaitanya >
There are a number of issues with supporting SR-IOV and RSC on the same interface. Among them are the fact that we support 64 VFs, but only 32 flows for RSC. As such enabling both would likely result in little to no gains from RSC as the VFs could easily consume all of the flows. In addition there are a number of logistical issues in supporting RSC as several of the registers needed to configure it are only available in the PF, and the VFs do not have the ability to modify PF registers. Finally the VF driver as it was written does not support RSC. As a result you would likely cause data corruption or kernel panics in your guest should you actually enable RSC with SR-IOV enabled. My advice would be to use GRO on the VF instead of trying to enable LRO/RSC. This will give you similar benefits without the extra hardware overhead. Thanks, Alex ------------------------------------------------------------------------------ CenturyLink Cloud: The Leader in Enterprise Cloud Services. Learn Why More Businesses Are Choosing CenturyLink Cloud For Critical Workloads, Development Environments & Everything In Between. Get a Quote or Start a Free Trial Today. http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk _______________________________________________ E1000-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/e1000-devel To learn more about Intel® Ethernet, visit http://communities.intel.com/community/wired
