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Add docs for usbtop (#2378)

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This PR adds documentation for using usbtop, a program for monitoring
USB bus bandwidth. Many teams have been having issues with USB bus
bandwidth, and including a tool with the PhotonVision image that allows
them to monitor said bandwidth will likely prove beneficial.

This PR also documents lsusb, which can be used to get the max bandwidth
on USB buses. This is helpful as it gives us a basline for debugging
with usbtop.
This commit is contained in:
Sam Freund
2026-03-02 16:39:58 -06:00
committed by GitHub
parent 1cc9a2f2ff
commit 6b6e2c3724
1 changed files with 38 additions and 0 deletions
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38
docs/source/docs/troubleshooting/unix-commands.md
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@@ -132,3 +132,41 @@ journalctl --output cat -u photonvision -f
```
`--output cat` is used to prevent journalctl from printing its own timestamps, because we log our own timestamps.
### lsusb
[lsusb](https://linux.die.net/man/8/lsusb) is a command that can be used to find all the USB buses on a device. When run with the `--tree` flag, it will give you more information on the available ports and connected devices. See the example below.
```
photon@photonvision:~$ lsusb -t
/: Bus 001.Port 001: Dev 001, Class=root_hub, Driver=xhci_hcd/4p, 480M
|__ Port 001: Dev 002, If 0, Class=Video, Driver=uvcvideo, 480M
|__ Port 001: Dev 002, If 1, Class=Video, Driver=uvcvideo, 480M
|__ Port 001: Dev 002, If 2, Class=Audio, Driver=snd-usb-audio, 480M
|__ Port 001: Dev 002, If 3, Class=Audio, Driver=snd-usb-audio, 480M
|__ Port 002: Dev 003, If 0, Class=Video, Driver=uvcvideo, 480M
|__ Port 002: Dev 003, If 1, Class=Video, Driver=uvcvideo, 480M
/: Bus 002.Port 001: Dev 001, Class=root_hub, Driver=xhci_hcd/4p, 5000M
|__ Port 003: Dev 002, If 0, Class=Vendor Specific Class, Driver=ax_usb_nic, 5000M
/: Bus 003.Port 001: Dev 001, Class=root_hub, Driver=xhci-hcd/1p, 480M
```
The most important information from this list is the bandwitdth. This is the last number we see, followed by an M (megabytes).
### usbtop
[usbtop](https://github.com/aguinet/usbtop) is a program that can be used to monitor traffic on your device's USB buses. To use it, run `sudo modprobe usbmon` then `sudo usbtop`. An example output can be found below.
```
Bus ID 1 (Raw USB traffic, bus number 1) To device From device
Device ID 1 : 0.00 kb/s 0.00 kb/s
Device ID 2 : 141.71 kb/s 23595.81 kb/s
Device ID 3 : 0.13 kb/s 0.13 kb/s
Bus ID 2 (Raw USB traffic, bus number 2) To device From device
Device ID 1 : 0.00 kb/s 0.00 kb/s
Device ID 2 : 450.42 kb/s 17.45 kb/s
Bus ID 3 (Raw USB traffic, bus number 3) To device From device
Device ID 1 : 0.00 kb/s 0.00 kb/s
```
The above output can be used to debug USB bandwidth issues, by comparing the size of data being sent with the bandwidth limits (bandwidth limits can be found using lsusb).