Ed, I think this is bug, not a feature. People expect scrolling and updates
to be smooth these days, the fact that we deliberately break it just
signifies very weird preferences somebody made while developing the code.
The fact that it "looks fine when scrolling stops" is no execuse IMHO.


On Thu, Jun 30, 2016 at 6:42 AM, Ed Schouten <e...@nuxi.nl> wrote:

> Hi Maxim,
> 2016-06-28 21:14 GMT+02:00 Maxim Sobolev <sobo...@freebsd.org>:
> > P.S. Just if somebody is interested in fixing those "fast scrolling text
> > turns into garbage" display issues, here is some screenshots of one of my
> > 11-alpha3 systems captured with a camera at 120fps. As you can see text
> > tears down quite badly.
> What happens is that rendering of vt(4) is done asynchronously. In
> addition to the screen contents, vt(4) keeps track of a rectangular
> area of the screen that needs to be updated. During every refresh, the
> rendering thread extracts and resets the coordinates of the
> rectangular area and redraws that area. It only holds a lock while
> extracting the rectangle's coordinates; not when redrawing.
> This means that if you have a lot of updates and redrawing is slow,
> you will get 'random' garbage on screen. Once output stops, the screen
> contents get refreshed one final time, making everything look all
> right again.
> --
> Ed Schouten <e...@nuxi.nl>
> Nuxi, 's-Hertogenbosch, the Netherlands
> KvK-nr.: 62051717
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