Comments on: Degrading qemu performance in DooM

By: neozeed

neozeed — Mon, 27 Sep 2021 13:34:41 +0000

In reply to Stefan Ring. Oh wow l! It’s been so long I’d forgotten it’s ticks to completion. Cross is definitely the way to go

By: Stefan Ring

Stefan Ring — Mon, 27 Sep 2021 13:29:33 +0000

In reply to neozeed. Setting up the cross build was a bit painful, but it’s definitely the better route. So I don’t need to employ a 2 decades old distro anymore. Yay! ;) Do note, however, that higher numbers correspond to lower performance for the Doom benchmark.

By: neozeed

neozeed — Sat, 25 Sep 2021 01:34:23 +0000

In reply to Stefan Ring.

yes the much later versions are faster! Like so much things change with time.

I built a cross compiler gcc 3 chain to build 0.9 as downloading so much crap and VM’s… yuck.

The one thing for me at least is that 0.9 feels more hackable, and smallish to work with, I still haven’t managed to get the latest stuff to build for Windows. I guess I should be cross compiling that as well. 😐

By: Stefan Ring

Stefan Ring — Fri, 24 Sep 2021 19:45:37 +0000

In reply to Stefan Ring.

Redoing the benchmarks because I just noticed that you used option a, while I chose option b. So these are the results for a:

0.90: 110
5.1.0: 308
6.0.0: 419/347 (32/64 bit)

By: Stefan Ring

Stefan Ring — Fri, 24 Sep 2021 19:29:37 +0000

I wanted to give your qemu 0.90 a try for a long time, and only recently found some time to do so and revisit this. After painfully managing to build old gcc 3.4.5 into something runnable on Fedora 33 (using RedHat Linux 9 of all things), the 32bit qemu 0.90 produced by this process gave me a doom score of 407. By contrast, a 32bit build of qemu 6.0.0 on the same system, using the system compiler gcc 10.3.1, produces a hideous score of 2583. The corresponding 64bit build at least reaches 2037. And as a cross-check that I did not somehow mis-configure it completely, the Fedora binary of qemu 5.1.0 gives me 1793.

But my impression is that this is not specific to Doom. I remember running Windows 2000 on my old MacBook back in 2008 using some qemu 0.9x binary not built by me, and the performance was quite acceptable. The same cannot be said about running Windows 2000 on current versions of qemu.

By: neozeed

neozeed — Mon, 18 Mar 2019 07:52:45 +0000

In reply to buricco.

I see it’s also been ported to the Amiga!

Although I haven’t the slightest idea what is involved in either porting or writing apps for it..

It looks like AES and all the video stuff is part of it too.

By: buricco

buricco — Mon, 18 Mar 2019 03:51:16 +0000

In reply to neozeed. EmuTOS. GEMDOS is the part of EmuTOS that corresponds to DOS on x86.

By: neozeed

neozeed — Sun, 17 Mar 2019 11:36:23 +0000

In reply to buricco.

I’ve seen TOS or opentos or whatever it’s called ported to that DIY kiwi68008 board. I think the Amiga too.

No idea through software how hard to port to a ficticous 68000 with a linear frame buffer like mode 13vga is…

Itd be pointless, but kinda funny

By: buricco

buricco — Sat, 16 Mar 2019 23:39:18 +0000

In reply to neozeed.

The only other CPU I know with an MS-DOS-like OS for it is the 68000 which has two (GEMDOS on the Atari ST, and whatever the X68K uses).

But I suppose some parts of the FreeDOS kernel could be ported to another CPU, maybe…

By: neozeed

neozeed — Fri, 15 Mar 2019 15:16:34 +0000

In reply to Artyom Tarasenko.

It’d be cool if there was some MS-DOS like OS for other processors… I feel that Linux is a bit heavy handed, but I may have to give that a go.

I’m starting to wonder if it jit/interprets GCC generated code better.