On 01/15/2014 11:34 AM, Chaitanya Lala wrote: > Hi Alex, ... > > On 1/15/14 8:12 AM, "Alexander Duyck" <alexander.h.du...@intel.com> wrote: > >> You mentioned using a 3.15.1 driver for the PF, I was wondering what >> version of the ixgbevf driver it was you were using? > 2.12.1 i.e. latest > >> The older versions >> of the VF drivers used an older single buffer approach to receive and it >> is possible that some of that 40% drop you are seeing is due to >> differences in the driver instead of a difference in features. If >> nothing else one thing you might try testing is the NIC passthrough >> without RSC to verify how much of the benefit is the RSC versus >> differences in the drivers. > > NIC Passthrough of a X540 NIC into a Ubuntu VM (single core) running > ixgbe-3.15.1, drops about 37.5% when using only GRO vs LRO/RSC. > Again - only using a few flows. > >> One significant factor that can limit the performance of virtualization >> is interrupt moderation. One of the effects of RSC is that the >> interrupt rate can be reduced due to the fact that the number of packets >> is reduced due to coalescing. Have you tried using the ethtool -C >> option to configure the Rx interrupt rates so that they are the same in >> both tests? > I did not use ethtool but instead the module parameter > InterruptThrottleRate (present both in ixgbe and ixgbevf) > and set it to 1000 for all my tests. The 40% drop is with this set. Are > you saying that I need to increase this value to > "adaptive" ? > > Thanks, > Chaitanya >
Are you measuring the drops percentage or the actual performance? One possibility if you are measuring drops is that you may need to increase the interrupt throttle rate as an ITR of 1000 is a bit excessive. I would recommend a value somewhere in the range of 4000 to 10000 for a VM in order to allow enough time for the descriptor ring to be cleaned. One alternative you may want to consider would be to use macvtap interfaces with a virtio adapter in the guest instead of direct assigning VFs. The advantage of that is that you then can use the RSC in the PF and pass the aggregated frames off to the VM. 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 E1000-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/e1000-devel To learn more about Intel® Ethernet, visit http://communities.intel.com/community/wired
