T7 Terrible streaming performance problems with latest driver | LabJack
 

T7 Terrible streaming performance problems with latest driver

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Matt C
mcarle's picture
T7 Terrible streaming performance problems with latest driver

We have been working with the T7 units and have noticed some issues with performance of streaming, namely CPU usage, between driver versions.  When running even the streaming example we are seeing 4.5-4.8% CPU usage when running "stream_callback.py" on driver version 1.19.0 on my Mac and 105% with the same script using 1.20.0.

We are getting similar results on Fedora (driver version 1.20.01) as well as on CentOS

Testing has all been done using the stock script so I seems unlikley it is related to anything we are doing in our actual implementation.

LabJack Support
LabJack Support's picture
Thanks for reporting this. I

Update: LJM 1.2100 fixes this issue.

 

Thanks for reporting this. I've confirmed that this is an issue. It is localized to SetStreamCallback, as far as I can tell.

  • LJM 1.1900: stream_basic.py ran at 58%. stream_callback.py ran at 17%
  • LJM 1.2000: stream_basic.py ran at 58%. stream_callback.py ran at 111%
  • LJM 1.2001: stream_basic.py ran at 3%.  stream_callback.py ran at 103%
  • LJM 1.2100: stream_basic.py ran at 2%. stream_callback.py ran at 13%

So two workarounds while we fix this are:

  1. Use LJM 1.1900
  2. Use eStreamRead without SetStreamCallback

 

Edit: Added LJM 1.2100 stats.

Matt C
mcarle's picture
Perfect, thank you so much

Perfect, thank you so much for the quick response.  We will revert to 1.1900 for now.  Any idea on when we might see a new driver?

LabJack Support
LabJack Support's picture
We will release a new

We will release a new installer within a few weeks as long as nothing unexpected comes up.

I'll update this thread when that happens.

LabJack Support
LabJack Support's picture
I forgot to update this

I forgot to update this thread at the time, but there is a new beta release of LJM that fixes this:

https://labjack.com/support/software/installers/ljm