AM5748: QT EGLFS backend idles at 50% cpu

Jonathan Cormier

Part Number: AM5748

Running any qml qt demo app using platform eglfs on the AM57x processor sdk filesystem results in 50% cpu usage when GUI is not doing anything. If you run the same qt application using Wayland, CPU usage is ~2%.

We are trying to use eglfs for less overhead however this extra cpu usage is slowing down our app.

Is there a known issue with the eglfs_kms driver? Is there anything I can do to prevent this?

# ThermostatDemo

# killall weston

# ThermostatDemo -platform eglfs

[ 335.371694] omapdss error: HDMI I2C timeout reading EDID
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
QPixmap::scaleHeight: Pixmap is a null pixmap

over 4 years ago

0 Jonathan Cormier over 4 years ago

Genius 3851 points

Reattaching broken images

Wayland

EGLFS

0 Jonathan Cormier over 4 years ago in reply to Jonathan Cormier

Genius 3851 points

Running perf seems to point to select taking up a lot of cpu time

perf top -F 99 --call-graph dwarf

0 Hemant Hariyani over 4 years ago in reply to Jonathan Cormier

TI__Expert 8385 points

Hello Jonathan,

Apologies for the delayed response and thank you so much for the analysis. We are looking into this internally.

What is strange is the fact that most of the time that is being spent in kernel framework functions. For example drm_poll hardly takes any time and that is the one that should have been called internally. Select should have just returned or blocked (scheduled out) if the fd wasn't ready. We will review this further and get back.

Regards

Hemant

+1 Krunal Bhargav34 over 4 years ago in reply to Hemant Hariyani

TI__Mastermind 44575 points

Hello Jonathan,

I removed the patch "0001-eglfs_kms-enhance-the-QPA-for-multiple-display-and-u.patch" and rebuilt Qt package. I tested the below package on my beagle X15 board and the cpu usage is extremely low. I have attached the new Qt package and please run the command "opkg install *.ipk" on targetfs to install the new libraries.

Regards,
Krunal

eglfs_test.tar.gz

0 Jonathan Cormier over 4 years ago in reply to Krunal Bhargav34

Genius 3851 points

Thanks Hemant and Krunal,

Good to hear you were able to reproduce the issue. I'll try the modified package. Are you going to keep looking into what's going wrong with the select call?

0 Hemant Hariyani over 4 years ago in reply to Jonathan Cormier

TI__Expert 8385 points

Jonathan,

Did the modified package work for you? Can we close this ticket now? We will raise the select issue internally but cannot comment on resolution yet. Really appreciate your help with getting to narrowing this down to one call.

Regards

Hemant

0 Jonathan Cormier over 4 years ago in reply to Hemant Hariyani

Genius 3851 points

Thanks. I've not had time to test this again but it sounds like your mods will work around the issue. Hopefully you guys can fix the PageFlip for the next SDK release.

Processors

Processors forum

AM5748: QT EGLFS backend idles at 50% cpu