06-15-2017 11:02 AM
In LabVIEW 2017 there is a new DVR option, Parallel Read Access. In this mode...
When the border node on the right is unwired, LabVIEW allows multiple, concurrent read-only operations and does not modify the data value reference.
I was wondering whether anybody has tested this mode for speed. In some VIs, sorry I cannot post them, it appears slower while in others faster. I am not sure when to use this mode. For me, it seems any read only operation should be better in this mode (even just a single access), however, in my testing this is not the case.
Anybody else out there test this new feature and can offer some thoughts?
Thanks
mcduff
06-19-2017 11:21 AM
Hi,
Could you post an example code of this?
Regards!
06-19-2017 11:27 AM
I can't post my application due to company policy, but something similar to the diagram below.
06-19-2017 08:16 PM
I ran the code below and saw pretty comparable results between the read only and the read/write.
Let me know if you see much difference in speed with the above
06-19-2017 10:30 PM
Maybe my example was bad. For this other case I can describe and show some code. I am downloading millions of points from a DAQ device, before plotting the data I do a Min/Max type of decimation so I plot a few thousand points instead of a few million. Below is the outer VI
The array is not being modified at all in this case, just read.
The subVI inside the in-place structure looks like this
Maybe its slower because I'm reading chunks of the array, not really sure. I do know if I put High Precision timers on the outside of the loop it is faster without the Read Only mode.
Thanks for looking into this.
mcduff
11-27-2017 12:05 PM
Am I missing something here? Does this not work for Classes in DVRs?
11-27-2017 12:18 PM
The read-only feature does not work with classes in 2017 although this is a bug. CAR 671221 was filed to address this.