Wait for vertical retrace, that is when the video beam goes dark and returns from the bottom line to the top line. Useful to synchronize animation with monitor refresh.
However, Linux is a multiuser OS, thus some time might have passed already when the function returns. Also, not all cards support this in all modes (or with more or less good results).
svgalib(7), vgagl(7), libvga.config(5), scrolltest(6),
This manual page was edited by Michael Weller <email@example.com>. The exact source of the referenced function as well as of the original documentation is unknown.
It is very likely that both are at least to some extent are due to Harm Hanemaayer <H.Hanemaayer@inter.nl.net>.
Occasionally this might be wrong. I hereby asked to be excused by the original author and will happily accept any additions or corrections to this first version of the svgalib manual.