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? 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.
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? If not I would recommend doing so as you may find that it will help to improve the Rx performance by reducing the number of interrupts. Thanks, Alex On 01/14/2014 04:08 PM, Chaitanya Lala wrote: > Thanks for your response. > I did tests with GRO enabled on the VF but got around a 40% drop in > throughput tests compared to a X540 NIC passthrough (with RSC/LRO enabled). > I was only using a couple of TCP flows so it did not hit 32 flow limit. > Both tests were done on a Ivy Bridge E3-1200 CPU on a single core Ubuntu > VM (so no RSS effects etc). > Do you have any est-results you could share which indicate similar > performance for GRO and RSC/LRO ? > > Thanks, > Chaitanya > > On 1/14/14 3:02 PM, "Alexander Duyck" <[email protected]> wrote: > >> 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. ------------------------------------------------------------------------------ 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
