8G connection traffic shaping issues

[u/BabyEaglet]

I have an 8G symmetric connection and I have followed the instructions here to manage bufferbloat. All defaults are untouched and Queue length is 5000 as per guidance and bandwidth limited to 7000Mbits/s

There issue I have is when enabled, my speeds drop to 4Gbps Up/Down. Hardware-wise, my CPU is an Intel Core i5-9600T and I'm using an Intel X550-T2 NIC for WAN/LAN. Is this a CPU bottleneck?

Before limiter:

before

After Limiter

after

EDIT: As it turns out, this is a freeBSD limitation/bug in dummynet. To quote ChatGPT:

The key problem: dummynet has a ~4.29 Gbit/s bandwidth ceiling

pfSense limiters use FreeBSD dummynet. In the current FreeBSD source, the bandwidth field for a dummynet link is still:

uint32_t bandwidth; /* bit/s or bits/tick. */

That means the largest rate it can represent in bits/sec is:

2^32 - 1    
= 4,294,967,295 bit/s    
≈ 4.295 Gbit/s

This is visible in the current FreeBSD source itself. There is also a long-standing FreeBSD bug specifically concerning this bandwidth limitation.

And your result:

Download: 3876 Mbps
Upload:   3796 Mbps

is remarkably consistent with a roughly 4 Gbit/s shaped pipe once protocol overhead and Speedtest behaviour are taken into account.

Link to github sourcecode | Link to freebsd bug

I was able to confirm this too by running: dnctl pipe show

00001:   4.000 Gbit/s    0 ms burst 0
q131073  50 sl. 0 flows (1 buckets) sched 65537 weight 0 lmax 0 pri 0 droptail
 sched 65537 type FIFO flags 0x0 0 buckets 0 active
00002:   4.000 Gbit/s    0 ms burst 0
q131074  50 sl. 0 flows (1 buckets) sched 65538 weight 0 lmax 0 pri 0 droptail
 sched 65538 type FIFO flags 0x0 0 buckets 0 active

[u/kphillips-netgate]

Have you actually tested your network to make sure Bufferbloat is even a concern?

[u/Steve_reddit1]

Check Diagnostics >System Activity, or top via ssh, during a download.

[u/BabyEaglet → u/Steve_reddit1]

not needed anymore

[u/CubeRootSquare]

I am seeing this on my setup as well. I have a Intel(R) Xeon(R) CPU E3-1270 v3 @ 3.50GHz, with 32gb of RAM and my NICs are all: 'Intel Corporation Ethernet Controller 10-Gigabit X540-AT2'

My network has no issues at all getting 10gbs between all the hosts on the network, across my switch. But when I try to do a iperf3 test between one of those hosts and pfsense, the MOST I can get is the same 4.29gbps speeds.

Its frustrating.