▲ | Animats 2 days ago | |
There's something to be said for not having a dumb VGA controller. Some years ago, I had a headless system running QNX in a control application. About 30% of the CPU time was being consumed by something. It turned out that the system had a very minimal VGA controller, not connected to anything. The QNX boot image was capable of running with no console at all, which was the intent. But it found the VGA controller and launched a screen saver. The screen saver worked by shifting the entire screen one pixel at a time, which, with this minimal VGA controller, was a very slow read from VRAM, one byte at a time. This was so slow that it ate up a huge amount of CPU time. This being QNX, it wasn't at high priority, so the real time stuff preempted it. |