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bnoordhuis / tkgate

A graphical editor and event-driven simulator for digital circuits
https://bnoordhuis.github.io/tkgate/
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Bad performance scrolling/dragging schematics with Ubuntu 18.04 #4

Closed esteban-stafford closed 5 years ago

esteban-stafford commented 5 years ago

Hello,

at the University of Cantabria (Spain) we use TkGate to teach computer architecture. We have simple implementations of both MIPS and ARM processors and we teach pupils to add instructions to them. We even have pipelined versions of both processors. Until now we have have used TkGate with Ubuntu 16.04 and it has been a great experience. However, now we have to upgrade to Ubuntu 18.04, and TkGate is not performing well. The refreshing of the schematics window when scrolling or dragging components is really slow.

I have tried the latest version of the code on different machines desktop/laptop and observed the same problems. I have a feeling that the problem lies in X, since I copied the binary compiled in 18.04 to a 16.04 machine and it worked properly. Nevertheless I wonder if you could reproduce the problem and offer some hint.

Thank you very much in advance,

Esteban

bnoordhuis commented 5 years ago

Hi, thanks for the report. Can you tell me more about your setup? I don't have 18.04 but I test on 19.04 and I don't see noticeably worse performance compared to older Ubuntu versions.

Does it make a difference when you use Wayland as the display server? You should be able to select it on the login screen. The default in 18.04 is X (while it was Mir in 16.04, I think) so that might make a tangible difference.

Also, if you have the opportunity to check with perf recordor perf top -p <pid> where the binary spends its time, that might shed some insight.

bnoordhuis commented 5 years ago

Closing, no follow-up.