Comment 13 for bug 1853357

Hi Jonathan,

you seem to be having several different issues here, so I'll try to address them individually.

First the slow updates, you wrote: "screen updates to the DisplayLink monitor are Extremely Slow. Like I am typing in a terminal window and it sometimes takes a second or two between when I type something and when the results of the typing show up in the terminal. If I move the same terminal window onto the built-in laptop display the lag goes away."

Slow updates could be one of two things: either the copying of content to DisplayLink itself is slow, or DisplayLink is showing outdated content. To understand which one it is, you could try running 'glxgears' (or any program that animates continuously and reports fps) on the DisplayLink output and then see if the same slowness with a terminal still happens.

If the issue is outdated content, then 'glxgears' by forcing repeated output updates should have the side-effect of making the slowness go away. Also glxgears should report the expected monitor refresh rate as fps (for a 60 Hz monitor I'd expect 58 - 60 fps). Your overall system CPU consumption could be somewhat high, but I would not expect any CPU core to be maxed out.

If the issue is bad performance in copying the content, then running glxgears should not make the slowness disappear. Instead, glxgears should report very low fps, and your system CPU usage may or may not be high. It would be interesting to know if you have any CPU cores maxed out busy.

In any case, I think we should talk about the slowness in a new bug report. Please, point me to it, if you file one.