Selecting buffer sizes strongly depends on the VNF workload. It is expected that VNF vendors benchmark their VNFs to measure the optimal buffer size configuration. The VMXNET3 DPDK buffers are typically compiled in the VNF-C which means that CSPs will not be able to change these values. Generally, higher buffer sizes provide improved performance, however, latency can also increase with larger buffers

The following example buffer sizes are verified to support data plane intensive workloads across various network functions and environments. However, they might not be suitable for all workload types.
Table 1. Example Buffer Alignment

Buffer Size

(ESXi SoftQueue: 6000)

Rx Tx
Physical NIC 1024 2048
vNIC 3000 4000

Recommendation

  • Use larger buffer sizes for better performance.