Slowiness and freezing with QMI SDK under Ubuntu


I’m quite desperate since I can’t understand the issue or find any solution on the web. Here’s my problem:
we’re developing a connected device and I’m trying to interface a sierra wireless card (MC7354) with our software.
The problem is that my solution is totally unstable. The software can start the SDK and connect to the network the first time. I can stop / start the connection multiple times without problems (or it appears to have no problem).
But when I try to restart the QMI SDK (we have a button to manually reset the connection), it just impossible to start a data session and the all system is slow or just blocked. In fact, our software tries to launch other processes during its workflow (through QProcess) but they’re simply failing to start after i’ve restarted the QMI SDK. And when I try to diagnose the issue, basic linux commands don’t start. It seems the system is blocked on an obscure system call.

Here’s what my software does basically when connecting (the software starts the SDK process):

And when resetting the connection:
SLQSKillSDKProcess -> which can fail…
pkill -9 slqssdk // to be sure, i guess it’s not a good idea

My system: 3.8.0-44-generic #66~precise1-Ubuntu SMP Tue Jul 15 04:04:23 UTC 2014 i686 i686 i386 GNU/Linux (ubuntu 12.04, quite old…)
And our software is built upon Qt 4.8 (quite old too)

Thanks in advance for your help. If you need anything, please, ask me.


Hi François,

The issue may not be SDK related.
Try to monitor the processes with top utility in a different console to figure out what is eating up the CPU.
kill -9 should be fine.

Do you see the same problem when you launch the SDK connection manager sample app?
I assume you are using the Sierra drivers.
You can also try SDKlite which has no SLQSSDK process.