FS#49989 - [konsole] very high CPU usage

Attached to Project: Arch Linux
Opened by Andrej Podzimek (andrej) - Thursday, 07 July 2016, 15:44 GMT
Last edited by Antonio Rojas (arojas) - Tuesday, 02 August 2016, 08:04 GMT
Task Type Bug Report
Category Packages: Extra
Status Closed
Assigned To Antonio Rojas (arojas)
Felix Yan (felixonmars)
Architecture All
Severity Medium
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 4
Private No

Details

Description:

Both yakuake and konsole exhibit a very high CPU usage, usually around 50% of one processor's. When running a program that redraws the terminal, such as htop, CPU usage of the terminal application quickly reaches 100%.
This problem appeared at the same time as https://bugs.archlinux.org/task/49988 and is most likely related. It also correlates with an unexpected latency upon startup for virtually all terminal programs.
Desktop acceleration (compositor) is on, KWin acceleration looks OK and applications such as KWrite have no similar symptoms, i.e., they start immediately and their CPU load is negligible, as usual).

Additional info:
* package version(s)
yakuake 3.0.2-3
konsole 16.04.2-1
qt5-base 5.7.0-1

* config and/or log files etc.
Some log files are in https://bugs.archlinux.org/task/49988, but none of them seems to expose anything directly related to konsole/yakuake.

Steps to reproduce:
This task depends upon

Closed by  Antonio Rojas (arojas)
Tuesday, 02 August 2016, 08:04 GMT
Reason for closing:  Fixed
Additional comments about closing:  qt5-base 5.7.0-2
Comment by Andrej Podzimek (andrej) - Thursday, 07 July 2016, 15:46 GMT
The problem looks exactly the same with compositor switched off.
Comment by Andrej Podzimek (andrej) - Thursday, 07 July 2016, 22:03 GMT
Update: As outlined in https://bugs.archlinux.org/task/49988#comment148792, I think this problem is completely unrelated to the sddm issue.
I've found a workaround for the sddm issue, but huge latency and CPU usage in konsole and yakuake still persist, with the compositor or without it.
Comment by Sebastian Ziebarth (voeck) - Friday, 08 July 2016, 09:04 GMT
You are not alone. I can confirm this problem with konsole. I see exactly the same issue here. It began after I rebooted after two weeks of uptime - so I can't really tell which upgrade caused it. Perhaps it is related to the freetype2 upgrade?
Comment by Sebastian Ziebarth (voeck) - Friday, 08 July 2016, 09:15 GMT
My guess seems right. If you set FT2_SUBPIXEL_HINTING="0" the issue is gone. FT2_SUBPIXEL_HINTING="1" and FT2_SUBPIXEL_HINTING="2" cause the problem in konsole.
Comment by Antonio Rojas (arojas) - Friday, 08 July 2016, 10:33 GMT
Possibly related: https://bugs.kde.org/show_bug.cgi?id=354082
Comment by Andrej Podzimek (andrej) - Saturday, 09 July 2016, 00:43 GMT
I can confirm that switching subpixel rendering off in systemsettings5 is a workaround also on my system. The CPU usage of yakuake running htop dropped from 100% to ~1% once I switched subpixel rendering off. Quite a difference. All the showing and hiding delays are gone.
Comment by Vladimir (vova7890) - Tuesday, 12 July 2016, 10:33 GMT
if rollback freetype2 to 2.6.3 - problem is gone
Comment by C.D. (stophe) - Wednesday, 13 July 2016, 21:03 GMT
Hello
Same issue with konsole and Monospace font. konsole is slow until I set another font like Terminus.
I will try the 2 above solutions

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