console in 11.0-ALPHA4

[Ed Schouten]

Hi Maxim,

2016-06-28 21:14 GMT+02:00 Maxim Sobolev <sobomax at 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 <ed at nuxi.nl>
Nuxi, 's-Hertogenbosch, the Netherlands
KvK-nr.: 62051717