Touchscreen CPU load on a716

[Dan East]

After some initial testing I'm seeing a big hit on the a716 when the touchscreen is in use. Around a 50% drop in FPS. Can anyone else verify this? Has anyone found a solution to this performance issue that basically all Pocket PCs exhibit? Supposedly Tomb Raider does not slow down when the stylus is in use. This could be the result of it already running at a low FPS, an inaccurate (or purposefully fudged) FPS counter, or they actually identified and found a way to correct the problem.

Here are existing threads on the issue:
http://www.pocketmatrix.com/forums/view ... hp?t=10065
http://www.pocketmatrix.com/forums/view ... hp?t=13790
http://www.pocketmatrix.com/forums/view ... hp?t=13497

Dan East

[rcp]

[Dan East]

[rcp]

[j.edwards]

[Johan]

[joshbu [MSFT]]

I took a look in the message queing code. Each message que in CE has a an event associated with it that gets signaled when a new message has been entered into the que. GetMessage's primary difference from PeekMessage is that it calls WaitForSingleObject on that event.

All of the low power magic is happening in the WaitForSingleObject routine.

So, you should be able to reap low power goodness with either loop, so long as when you use PeekMessage, you still give some cycles back to the OS in some way: a Wait* or a Sleep.

Now, I'm afraid that I can't answer why the touch driver performance would improve in that case. Perhaps it is multithreaded and giving up a few cycles allows the touch worker threads to do work in a more timely fasion? <shrugs>

[Dan East]

[joshbu [MSFT]]

[Dan East]

[rcp]

[Tala]

[j.edwards]

rcp: have you done any tests to see if the WM_TIMER msgs queue up?

joshbu: you mentioned events being "merged" - does this apply to WM_TIMER messages also?

[joshbu [MSFT]]

[Digby]