dosbox 0.73b alpha to test

Hi all,

I've spent again time trying to optimize dosbox. It is diffult because the core is almost impossible to change. I did some things that can bring improvements but I need people to test it, mostly on Sam on which performance difference will be easier to see.

You can download it here. I will only finalize it and put it on os4depot if it shows improvements.

Thanks !

@corto

Tryed. Tested "Mortal Kombat 3" game. Visually all looks the same. Maybe, a bit faster loading, a bit faster starting of emulator itself. But game itself (related to graphics rendering speed) are the same. That all on Peg2 with 1ghz.

Some days ago i also tested dosbox (win32 vesion), on PC where 1ghz of cpu was too. It feels faster on 4-5 times if compare with aos4 version. Mortal Kombat 3 just works madness fast. I know that is not so correct to compare x86 emulator on x86, with x86 emulator on ppc, but still, speed of cpu are the same ..

One man on russian forum, say this (maybe it can help you in future with dosbox porting):
---
On win32 dosbox use "recomplier". That only done for now for x86 and ARM only (and because of it it works so fast). In general, if write such recompiler for PPC, then, dosbox will fly on PPC too. And that must be not so hard, just need to learn PPC asm a bit
---

Not sure will it helps or not ..

ps. Btw, i also tryed dosbox on AROS , with these diskmags about we talk before (hugi, etc) with wrong colors. And on AROS it works fine -> that mean, that problems 100% in the BIG/LITTLE endian modes, when it start to works with protected mode.

@corto

Thanks corto, this is exactly what I need for my Flex, previous release seems very very good as compatibility but an hell as speed

For my experience Civilization 1 was the only game playable, Mortal Kombat series for example was decent only removing all gfx's beauties ...

I will test soonish!

P.S.
Did you try this lib ?

http://www.os4depot.net/index.php?fun ... /library/ibm_perflibs.lha

@samo79

Corto knows about the perflibs. He didn't use them as he knows it wouldn't make a difference.
Corto uses the profiler he ported to OS4: Hieronymus

@Elwood

Ok, thanks

@corto

Just tryed Mortal Kombat 1 but it's the same, off course I need more testing, need to explore all the various configuration, not to mention about game's details..

I'll keep you informed as I need this emulator as a piece of bread

No, I didn't use ibm_perflibs because in dosbox almost all the time is spent in the core (decoding x86 and doing huge computing) : I tried to reorganize some things to avoid cache misses (access data puting it on the same cache line, prefetch on data), improve branch prediction, add ... but I am not sure the effect is visible. It is only possible to optimize some peripheral parts (what means few percents).

The big improvement would be to write a dynamic core (called recompiler in a previous post) producing PPC code. Do you know why dosbox is so slow on PPC ? Not because PPC is bad, it is even very good (I was impressed : sometimes I thought I had found something to optimize and the compiler already did it !).
It is slow compared to x86 versions because it does not use JIT technology.

I will look again at the code to see how hard it is but nothing is documented and the code is a mess even if at the end the program is very good ...

Elwood : About Hieronymus, I didn't port it to OS4, I created it And yes, again with dosbox, I can confirm it list the same slow functions than oprofile on Linux.

kas1e : About Hugi and x-ray, I tried of course and even on Linux PPC there is a problem with colors. I checked SDL surfaces and their masks, they are good. I thing these programs access hardware in a different way ... I don't know if we could fix that.

@corto
Works well on my SAM 800 Flex. Just played Centurion and a bit of Warcraft both very playable. Thanks

ace

@acefnq (and others) : Does it run better than the previous version (available on os4depot) looking at a CPU meter ?

Thanks for the tests.

@corto

Quote:
Oh, I wasn't sure about it so I prefered to say "port". Sorry

@corto
How and what do I need to do this"

Ace

@acefnq

Run for example CPU_watcher, and just check how cpu loading looks like on the same games for these 2 versions (os4depot one, and that one).

@acefnq

There are tools on os4depot :
- cpuwatcher
- cpuinfo_docky

They show the CPU activity (how many percents are used).

@corto

OK. With CPUwatcher the release before yours is:

Boot only to DOS 47-48%
Under load (Centurion) CPU 100%

Your version
Boot only to DOS 47-50% but mainly the same 47-48%
Under load (Centurion) CPU 100%

Both reads for under load are taken at gameplay not Intros.


Hope this helps.


ace

@acefnq

What is the value of the parameter Cycles in the config file ? Did you set it to "max" ? If I remember well, I chose 3000 cycles. Maybe you could decrease this value.

With 100% CPU, we know that there is not enough CPU power, so reducing the workload, to 80% for example we could see a difference.

@others : Any results ? Not interested in dosbox ?

Oh ... for people who will test, please tell me what is the machine you use. Thanks !

@corto

Give me qemu and I'll send you millions of tests

@corto

I'd be interested in trying it,but where do i find something to test?

@corto

Using CPUInfo on my Peg2 under 4.1 Update 1

0.73 @ idle 39%
Running Frontier and in game 44/45%


0.73b @ idle 34%
Running Frontier and in game 42/43%

Nothing to test but CPUinfo (SamFlex 800MHz) shows:

0.72 idle 44-45%

0.73b idle 49-50%

OK, now I see, cycle value in 0.72 is 2500, after changing cycle in 0.73b config to the same value (was 3000):

0.73b idle 43-45%

Enother edit:

Spear of Destiny:

0.72 100% almost all the time

0.73b 91-95%, 100% in some moments

@corto

AmigaONE XE G4 800MHz

Pinball Dreams 2

DosBox 73b: 50% - 75%
old version: 60% - 95%

@corto

Quote:

(Off-topic) It comes as a sort of surprise how easily you can reach 100% CPU usage on the SAM (667MHz at least). Try loading a long ASCII text file into MultiView and then use the scroller to move there and back.