[Bug 215475] RMNET data connection speed would be reduced to about 80-100Mb/s from 150Mb/s if try to re-connect it

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=215475

--- Comment #1 from Greg Kroah-Hartman (greg@kroah.com) ---
On Mon, Jan 10, 2022 at 11:23:13AM +0000, bugzilla-daemon@bugzilla.kernel.org
wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=215475
> 
>             Bug ID: 215475
>            Summary: RMNET data connection speed would be reduced to about
>                     80-100Mb/s from 150Mb/s  if try to re-connect it
>            Product: Drivers
>            Version: 2.5
>     Kernel Version: 5.13.0

Does this also happen on 5.16?

> Created attachment 300251
>   --> https://bugzilla.kernel.org/attachment.cgi?id=300251&action=edit
> iperf test result
> 
> We have a Qualcomm modem device which support MBIM and RMNET over USB.
>   For RMNET, the download-link speed would be reduced to 80 Mb/s if
>   re-connect
> it once. The expected speed should be 150 Mb/s.
>   Test step as below:
>   1. Switch device to RMNET USB composition.
>   2. Connect it to host PC(kernel 5.13).
>   3. Start a data connection with nmcli related settings.
>   4. Start a iperf test with simulated network(CMW500). Test result is about
> 145 Mb/s ,and protocol is TCP.
>   5. Disconnect the connection by turning off the signal, setting AT+CFUN=0，
>   or
> deleting the data connection in the host.
>   6. Re-connect it again.
>   7. The TCP iperf test could only reach to about 80-100Mb/s.

If you look at the usb traces, is the data the same?  Any long pauses?

thanks,

greg k-h

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