Atom E3950 Performance Question



  • I have my pfSense build running on an Atom E3950 (4 core) chip with 2 x i211 network ports for about a year now. I have not had a single issue. My ISP currently provides me with 400/40 speeds. I'm upgrading to 1G/1G fiber next month and had a few questions.

    1. I'm 100% sure the CPU will not be a bottleneck, but will I need to increase IGB buffers from pfSense default which is 1024 (I think) to keep up? I've seen a lot of posts on the forums of people increasing "hw.igb.rxd" and "hw.igb.txd" to 2048 or even 4096 for increased throughput.

    2. Will there be a need to increase the maximum interrupt rate from the pfSense default? I have also seen posts of people increasing this value to 32000 or 64000 (hw.igb.max_interrupt_rate)?

    3. Lastly, is there a need to mess with the network queue values (hw.igb.num_queues) or leave them at the pfSense default? I have seen online Intel recommends setting the number of queues to number of cores divided by number of ports which in my case would be 2 (4 cores/2 ports).


  • Netgate Administrator

    I would not expect you to need to change those values from their defaults to hit line rate there. However it likely won't hurt to test. You may reduce CPU load for example.

    The num_queues should be left at default. There was a time when it required setting lower but the driver has improved considerably since then. For best throughput each NIC should have a queue for each available CPU core to service. The i210 I believe it limited to 2 queues anyway, I'm insure about i211.

    Steve



  • Thanks for the info. i211 also has 2 queues.



  • @stephenw10 said in Atom E3950 Performance Question:

    The i210 I believe it limited to 2 queues anyway, I'm insure about i211.
    Steve

    My understanding is i210 has up to 4 queues and the i211 has up to 2. Which is why the MBT-4220 (4-Core) uses the i210 and the MBT-2220 (2-Core) uses i211.

    See table 1-6 on page 11...
    https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/i211-ethernet-controller-datasheet.pdf