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I'm testing a performance of DPDK-based OpenvSwitch implementation (github.com/01org/dpdk-ovs) on the following server:

  • Intel CPU Xeon E3 3.30Ghz
  • Intel 1G NIC I210
  • RAM 8G

Basically my setup includes two ports, traffic enters port0 and forwarded by dpdk to port1. The performance is quite low, although I isolated processes on distinct cores on the machine with DPDK software. I didn't do IRQ affinitization because DPDK has poll-mode user drivers.

Now I'm beginning to wonder, if a CPU speed of the server may have an impact on the overall performance? I mean with regard to NIC speed and packet processing performance, is it normal to slow down CPU, i.e. drop the frequency, in order to achieve better performance, or it sounds stupid?

Thanks.

Mark
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1 Answers1

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Its very unlikely CPU drops its packet processing cycles speed with respective to NIC processing capability. Ideally when NIC working at its full capacity, meaning when its packet buffers are DMA'ed to the system memory form NIC memory doesn't require any CPU cycles. And when DPDK PMD rte_eth_rx/tx_burst() performed to receive or transmit on two different physical CPUs(In your case) or on hyper-threaded lcores, then CPU cycles are required. Hence for better performance processing at NIC capacity, you might need additional cores but it doesn't slow down the CPU.

Sunil Bojanapally
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