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Touchscreen CPU load on a716

PostPosted: Apr 12, 2004 @ 10:14pm
by 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

PostPosted: Apr 13, 2004 @ 4:28am
by rcp

PostPosted: Apr 13, 2004 @ 6:01am
by Dan East

PostPosted: Apr 13, 2004 @ 6:26am
by rcp

PostPosted: Apr 13, 2004 @ 8:20am
by j.edwards

PostPosted: Apr 13, 2004 @ 9:35am
by Johan

PostPosted: Apr 13, 2004 @ 6:16pm
by 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>

PostPosted: Apr 13, 2004 @ 6:40pm
by Dan East

PostPosted: Apr 13, 2004 @ 7:04pm
by joshbu [MSFT]

PostPosted: Apr 13, 2004 @ 8:36pm
by Dan East

PostPosted: Apr 14, 2004 @ 4:10am
by rcp

PostPosted: Apr 14, 2004 @ 12:18pm
by Tala

PostPosted: Apr 16, 2004 @ 5:46am
by 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?

PostPosted: Apr 16, 2004 @ 7:42am
by joshbu [MSFT]

PostPosted: Apr 16, 2004 @ 7:47pm
by Digby