Error when trying to receive samples with UHD using two USRPs on the same ubuntu machine (USBError -11: usb rx6 submit failed: LIBUSB_ERROR_NO_MEM)

Question

I set up a Ubuntu server with 2x USRP B200 connected to it via USB. I can find both devices and am able to receive samples fine (without dropped samples) using the following command in my SSH shell:

./rx_samples_to_file --gain 55 --freq 1234e6 --rate 50e6 --ant "RX2" --ref "external" --wirefmt sc12 --file /recordings/test_1.iq --duration 60 --stats --progress --args num_recv_frames=1900,serial=0000001 (redacted the real SN)

^This results in solid streaming and recording as expected.

While the above runs, I want to also start recording with the 2nd USRP, so I run a 2nd shell in parallel and the following command:

./rx_samples_to_file --gain 55 --freq 1234e6 --rate 50e6 --ant "RX2" --ref "external" --wirefmt sc12 --file /recordings/test_2.iq --duration 60 --stats --progress --args num_recv_frames=1900,serial=0000002 (redacted the real SN)

^Once I run this command however, the following errors occur, and even the existing stream in shell 1 is stopped:

Error in shell 1:

    [...]
    50.0002 Msps
    49.9999 Msps

terminate called after throwing an instance of 'uhd::usb_error'
  what():  RuntimeError: USBError -11: usb rx6 submit failed: LIBUSB_ERROR_NO_MEM
Aborted (core dumped)

Error in shell 2 (in which we just tried to start the 2nd USRP stream):

Creating the usrp device with: num_recv_frames=1900,serial=0000002...
[INFO] [UHD] linux; GNU C++ version 12.4.0; Boost_108600; UHD_4.7.0.HEAD-release
[INFO] [B200] Detected Device: B200
[INFO] [B200] Operating over USB 3.
[INFO] [B200] Detected bad USB state; resetting.
[INFO] [B200] Detected Device: B200
[INFO] [B200] Operating over USB 3.
Error: RuntimeError: USBError -11: usb rx6 submit failed: LIBUSB_ERROR_NO_MEM

Any idea what I am doing wrong here? How can I make both streams run in parallel?

UPDATE: Interesting discovery: If I run both streams at default num_recv_frames it works fine. If I run one stream at my custom num_recv_frames=1900 and the 2nd stream at default num_recv_frames it ALSO works. But, if I run both with a custom num_recv_frames it breaks! (unfortunately I need the high custom num_recv_frames to get reliable streaming at this high sample rates to not have overflows) any ideas?

is this really a Ubuntu machine or is this Ubuntu running in WSL? — Marcus Müller
– Marcus Müller, Commented Oct 8, 2024 at 19:02
ubuntu-24.04.1-live-server-amd64 running as a VM on a xcp-ng host. I have a USB PCIe card passed via PCIe passthrough into it — Nils
– Nils, Commented Oct 8, 2024 at 19:04
btw, just noticed there is a possible interesting warning when starting up the stream on the 2nd USRP "Detected bad USB state; resetting" (can see it also in the error I copy-pasted in the original post) — Nils
– Nils, Commented Oct 8, 2024 at 19:12
Another idea: I did not replug the USRPs after I set the udev device rules, could that cause this issue potentially? — Nils
– Nils, Commented Oct 8, 2024 at 19:26
Interesting discovery: If I run both streams at default num_recv_frames it works fine. If I run one stream at my custom num_recv_frames=1900 and the 2nd stream at default num_recv_frames it ALSO works. But, if I run both with a custom num_recv_frames it breaks! (unfortunately I need the high custom num_recv_frames to get reliable streaming at this high sample rates to not have overflows) — Nils
– Nils, Commented Oct 8, 2024 at 20:46

Mohseen · Accepted Answer · 2024-10-21 11:24:54Z

0

may be you can try increasing the memory in /sys/module/usbcore/parameters/usbfs_memory_mb

answered Oct 21, 2024 at 11:24

Mohseen

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2 Comments

Nils Over a year ago

Thanks for the idea. Thats currently set to 16. What value do you suggest to change this to ? 32MB? (any impact changing this could have on the system/other devices?)

Mohseen Nov 25, 2024 at 7:46

Not sure on the impact, but atleast it helped me to run multiple B210 on the same machine.

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