Weston on framebuffer?

Christer Weinigel christer at weinigel.se
Wed Jul 20 19:49:57 UTC 2016


On 07/20/2016 01:04 AM, Carsten Haitzler (The Rasterman) wrote:
>> With this I managed to get a desktop and was unable to start
>> wayland-terminal.  Redrawing of the graphics felt fairly snappy, but the
>> lag from pressing a key on the keyboard until a character showed up in
>> the terminal was slow, probably between a quarter to half a second.
>> So my question is if this is the performance I should expect with weston
>> on a 400MHz ARM9 and a dumb framebuffer?  Have I done something stupid
>> and there are easy ways to speed it up?

> when you say redraw is snappy... that implies that output is fast. so time from
> deciding to render and update and it appearing is very short. but you seem to
> have serious input lag which implies to me that it has nothing to do with your
> cpu speed and is something else deeper and more involved. time to trace things
> and see how they go.

I put up a short video here:


On the framebuffer I don't perceive any lag at all between a keypress 
and the character appearing on the screen.

With weston-terminal running I can drag the window around and even 
though it's not very fast and there's a bit of tearing it isn't too bad. 
The response when dragging feels ok.  Keypresses feel laggy even though 
mouse motion doesn't, but I'm not sure if that's because I don't notice 
the lag when moving the mouse or if it is a real difference.

I tried to do a strace of weston-terminal, but it was a bit painful, it 
reads every file it can find in /usr/share/icons/default/cursors/ when 
it starts so strace took forever before the terminal would even show up.

And for trying to do more advanced tracing, I don't quite know where to 
start.  Are there any knobs in the source to do things such as dump 
timestamps for messages between the server and client?


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