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Unread 26-03-2010, 21:30
Greg McKaskle Greg McKaskle is offline
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Re: What does the Camera Slow Down?

I'll be happy to give a bit of guidance.

As with most profilers, it isn't hard, but getting good data and finding the needle in the haystack sometimes takes some finesse.

You will want to run in the developer account, or possibly run on a different computer -- its what I did. By the way, once you use it on the dashboard, you may find it useful on the cRIO too, if using LV.

The profiler is located under Tools>>Profile>>Performance and Memory. It opens the profile window. Open the project for the dashboard, open the dashboard panel, its diagram, start the driver station, killing the DB it opens if necessary. Open the profiler and ...

1. Press Start on the profile window.
2. Run the dashboard for five or ten seconds.
3. Abort the dashboard.
4. Press Stop on the profile window.

This should give you a table. Rows of VIs with columns for VI time, subVI time, and total time. To hunt for the hot spot, it is often useful to sort by different columns by clicking on the header above the column. Clicking on a row hilights it to more easily follow it and absorb what the row is telling you. Additionally, it is often useful to double click a VI row to see how that item was affected by subVI calls. This lets you see how common subVI calls are charged to different callers. You can right click on a row to access a contextual menu that aids navigation to hierarchy, to the VI, or to callers. You may also find it useful to turn on Timing Statistics (after the fact is fine). I don't use it for statistics so much as number of calls to spot n-squared algorithms, etc. Also useful (after the fact is fine) is the Timing Details to see drawing time, display time, etc.

Saving the profile data will put it into a spreadsheet file. You cannot load it into the profile window again, but you can make due with loading several sheets into Excel and doing your own before and after comparisons.

The profiler works at the VI level, meaning it is a little coarse, but since it is pretty easy to make subVI from selection, it is usually good enough to get you in the ballpark of the hotspot, and if not, you can introduce new profile VIs easily. Similarly, you can comment out code using the Diagram Disable structure to surround code.

Note:
The profiler only records and reports complete VI runs. If a VI was already running when the profiler was started, its time will not be in the report. For the complete picture, start the profile before you profile what you care about. If you know that you are calling into the subVIs where the hotspot likely is, you can Start mid-application and hit the snapshot button to see intermediates. This is very useful for ad hoc measurements, but be careful to remember what you aren't profiling by doing this.

Let me know what else is confusing. Hope this helps.
Greg McKaskle
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