Re: [libusb] Issues with low CDC_ACM throughput on STM32 USB-FS (sync/async)

[Xiaofan C. <xia...@gm...>]

On Sat, Apr 27, 2024 at 1:54 PM Jerri Lipp via libusb-devel
<lib...@li...> wrote:
>
>
> ST's USB middleware supports double-buffering and enabled by default. I verified
>  that the proper IFDEF branch is taken during compilation.
>
> Also, the issue is not that I'm not getting good throughput, but that in order to
> approach that 1MB/s mark I have to add phantom IN transfers on one computer,
> and (now that I've checked) that performance is actually worse on a much newer
> and more powerful laptop.

Get rid of the IN endpoint and make the device a generic USB device
(with Bulk IN
and Bulk OUT endpoint only), then use libusb again to see if that helps.

You may also want to give libusbK kBench a try to see how fast you can get
by testing the Bulk OUT endpoint only. Unfortunately there is no similar
example for libusb yet.

Reference:
https://github.com/libusb/libusb/issues/962
https://github.com/libusb/libusb/issues/951

I have no issues to get >1000KB/sec for a full speed USB device
(Microchip USB PIC) and >3Gbps with CyUSB FX3 SuperSpeed
device

I remember that Travis has done some benchmarks for STM32
device as well and the result is also >1000KB/sec.

FW source codes:
https://github.com/mcuee/libusbk/tree/master/BmFW

kBench source code
https://github.com/mcuee/libusbk/tree/master/libusbK/src/kBench

Reference discussion:
https://community.osr.com/t/benchmarking-winusb-libusbk-and-cypress-cyusb-driver/57390/3

437,800 KB/sec for cyusb3.sys using Cypress Cystream application
437,700 KB/sec for libusb0.sys using libusbk kBench application
386,600 KB/sec for libusbk.sys using libusbk kBench application
385,300 KB/sec for WinUSB using libusbk kBench application

You can also use libusb based libusbdotnet benchmarkcon example (v2
branch only).
https://github.com/LibUsbDotNet/LibUsbDotNet/issues/137

I tested with Cypress USB FX2LP and CyUSB FX3 there. It works well for
Bulk IN/OUT transfer, but not ISOC transfer.



--
Xiaofan