Re: Instruction Tracing

On 8/10/2024 6:20 PM, Lawrence D'Oliveiro wrote:

On Sat, 10 Aug 2024 17:49:42 -0500, BGB wrote:
 

Meanwhile, saw a video recently where someone had ported Doom to a 233
MHz PowerPC (running Windows NT4) machine and, its performance was not
good...
>
Not obvious is what combination of factors conspired to cause Doom to
apparently run at single-digit framerates.

 Windows NT never meant for games?

Windows GDI isn't fast, but it isn't usually *that* slow either.
WinQuake and Quake2 both used GDI to good effect.
If Windows GDI performance is seriously broken, this is a different issue from merely "not meant for games".
Normally, Doom is almost entirely self-contained, so there isn't likely that much area where OS APIs should effect all that much (apart from things like audio/graphics output, and checking for keyboard input).
Granted, that port using SDL could introduce some unknown variables here. AFAIK, "Chocolate Doom" is supposed to be a fairly direct port of the Doom engine (as opposed to heavily modified engines, like ZDoom).
Can note that my Doom port was based on Linuxdoom, but with some hacks to try to deal with Heretic and Hexen; before me noting that both Heretic and Hexen had source releases so I just ported these.
Doom generally runs fine at 50MHz, but can get a bit chunky at 16-20 MHz.
I am getting performance similar to that seen in the video, if I run Doom at roughly 12 MHz.
...