Driver Station Performance Improvements #97
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Locking the joysticks now uses a ReaderWriterLock, and we now get the descriptor in the GetData loop. This should speed up the DriverStation, and make it more reliable.
The GetData HAL methods take 5 ms combined to grab all the data. So there is easily a period where the data could be locked and contended for. This now grabs the data into a cache, leave all joystick data readable. It then grabs the write lock, does a quick reference swap, and unlocks. This way, the writing only takes a few nanoseconds, rather then 5 milliseconds. Should fix DS Joystick Tests The tests need to wait longer. Extends wait times Might need to actually figure out locking driver station.
Current coverage is
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I pushed these fixes upstream as well. Don't know if they'll get merged, but they might. I saw performance improvements for sure, so I might merge this after a few days of testing. |
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Since this actually fixes bugs, I've done some testing and it works better. Merging, closing #98. |
ThadHouse
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Jan 13, 2016
Driver Station Performance Improvements
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The old driver station code had some performance issues. It would cache the data under lock, which would take about 5ms. In addition, only 1 thread could read from the cache at one time, which could be a problem. So the code was changed to use a ReaderWriterLockSlim, as writes are called much less then reads. The second commit changes the code to use a cache to pull the data from the HAL, and then grabs the lock and does a reference change, which can happen much quicker.