how to solve bad performance in vi server

[luke-sky]

I'm useing vi server in a recursively programming structure in labview 7.1.

I have very bad performance result so i made a test comparing the speed of che various vi server call and the native.

my tests are:

normal calling.

vi server calling by reference node

vi server calling by invoke node

for each vi server calling type i tried:

unique reference calling

different reference calling

different reference, preloaded,  calling

the only 1 case i found a loosing of performace acceptable 24% respect the normal calling: vi server calling by reference node with unique reference.

unfortunately this kind of calling is able to catch come kind of recunsion an forbidden it and this calling wait all the time the end of the execution of the vi called.

All the oter kinds of caling have very bad performance: from 90% to 99,9% LESS then the normal calling (10 to 1000 times more in execution time).

In addition there is a prblem in invoke colling: if you execute a invoke node with wait until done true, the mouse pointer fliks with the busy icone. that heppens in all the possible configuration.

I would like ti know if someuone as some solution to this performance problem and if Labview 8.0 fixs this problems.

Best regarda.

ing. Luca Benvegnù

[carlo>]

Hi Luca,

I've made some researches for you and, what can I say is that there is a certain number of requests about "vi server performances". There are some things that are in general suggested in this situation:

1) Be "minimalist" about the use of images, graph,... And avoid Large data structures: wiring large structures into/out-of sub-VI's can take time: pass the smallest amount of data.

2) Avoid repeated calls. Calling the sub-VI's frequently, in a loop for example, create a call over-head that could be an issue. For the same reason put the "wait until" function with a specification of time in order to run loops only as often as strictly required.

However, about your question of fixing the problem with LabVIEW 8.0, I suggest you to download the Evaluation Version of LabVIEW 8.2 and try by yourself if performances are better.

I hope I've been of some help.

carlo>