Constant CPU usage of at least 20%

Question

Constant CPU usage of at least 20%

Closed this issue 9 years ago · 11 comments

When using any of the dothat.touch event handlers (e.g. @touch.on(touch.UP)), while running top I noticed that the python process is constantly using at least 20% CPU. This is the case even when I don't touch any of the buttons on the Display-O-Tron HAT. When I removed the @touch.on event handlers, CPU usage went down to pretty much 0%.

I tested the same thing with the dot3k.joystick event handlers (e.g. @joystick.on(joystick.UP)), but those seem to work just fine. Pretty much no CPU load while idle, so it looks like this problem only exists for the touch event handlers.

Could you guys please take a look at this?
Thank you very much in advance!

Answer 1 · 2015-10-25T11:14:21.000Z

The area of interest for this problem is the interrupt polling loop here: https://github.com/pimoroni/cap1xxx/blob/master/library/cap1xxx.py#L360-L371

I suspect that delay needs increasing- in fact there must be a minimum sensible time for it which I could look up or derive. I kept it low because I wanted a good response in Piano HAT, but never tried raising it.

Piano HAT uses the alert pins, however, so the GPIO read is way less expensive than the round trip to an i2c register that the library needs to make for DotHAT.

Answer 2 · 2015-10-27T17:16:36.000Z

I've updated cap1xxx to increase the delay from a microsecond ( completely bonkers and probably not even meaningful in Python ) to 5ms, which I think should be plenty fast enough for even Piano HAT. pimoroni/cap1xxx-python@ef34015

If you grab the cap1xxx library from GitHub and install it, hopefully your CPU usage will drop dramatically.

Answer 3 · 2015-10-30T14:24:46.000Z

Cool.
Will re-running the dot3k installation script update the cap1xxx library?

I'll take a look at it ASAP. ;-)

Answer 4 · 2015-10-30T14:30:26.000Z

Nope, you'd have to git clone the cap1xxx library and install that separately.

Answer 5 · 2015-10-30T14:33:07.000Z

Ah, okay.
Maybe a stupid question, but where and how do I install it?

Also, since other Display-O-Tron HAT owners might not be aware of the CPU usage, you might want to make sure that re-running the dot3k installation script also updates the cap1xxx library. ;-)

Answer 6 · 2015-10-30T14:59:09.000Z

Under normal circumstances it should go, but I haven't pushed the change up to pip yet. Try something like:

git clone https://github.com/pimoroni/cap1xxx
cd cap1xxx/library
sudo python setup.py install
sudo python3 setup.py install

Answer 7 · 2016-02-03T11:20:49.000Z

I was wondering, is this issue solved in the official installation? I still have CPU usage around 20% with active dothat.touch event handlers, but it could also be my crappy Python code 😅

Answer 8 · 2016-02-03T21:02:21.000Z

Issue still exists.

Answer 9 · 2016-02-24T10:16:40.000Z

I've pushed up version 0.1.1 to pip which should contain this fix: https://pypi.python.org/pypi/Cap1xxx

Would be interested in feedback! @capfuji @wujku

Answer 10 · 2016-02-24T17:29:22.000Z

Thanks! CPU usage is down from around 20 to 2.3 %. Touch buttons are still working as expected. Perfect 😊

Answer 11 · 2016-03-06T18:03:38.000Z

I guess this issue can be closed. Good work!