[dpdk-dev] L2fwd Performance issue with Virtual Machine

[Selvaganapathy Chidambaram]

Hello Everyone,

I have tried to run DPDK sample application l2fwd(modified to support
multiple queues) in my ESX Virtual Machine. I see that performance is not
scaling with cores. [My apologies for the long email]

*Setup:*

Connected VM to two ports of Spirent with 10Gig link. Sent 10 Gig traffic
of L3 packet of length 1500 bytes (with four different flows) from Spirent
through one port and received at the second port. Also sent traffic from
reverse direction so that net traffic is 20 Gbps. Haven't enabled SR-IOV or
 Direct path I/O.

*Emulated Driver:*

With default emulated driver, I got 7.3 Gbps for 1 core. Adding multiple
cores did not improve the performance. On debugging I noticed that
function eth_em_infos_get() says RSS is not supported.

*vmxnet3_usermap:*

Then I tried extension vmxnet3_usermap and got 8.7 Gbps for 1 core. Again
adding another core did not help. On debugging, I noticed that in vmxnet3
kernel driver (in function vmxnet3_probe_device) , RSS is disabled if *
adapter->is_shm* is non zero. In our case, its VMXNET3_SHM_USERMAP_DRIVER
which is non zero.

Before trying to enable it, I would like to know if there is any known
limitation why RSS is not enabled in both the drivers. Please help me
understand.

*Hardware Configuration:*
Hardware          : Intel Xeon 2.4 Ghz 4 CPUs
Hyperthreading  : No
RAM                 : 16 GB
Hypervisor         : ESXi 5.1
Ethernet            : Intel 82599EB 10 Gig SFP


Guest VM         : 2 vCPU, 2 GB RAM
GuestOS          : Centos 6.2 32 bit

Thanks in advance for your time and help!!!

Thanks,
Selva.