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FS-UAE Amiga Emulator
Performance
- Your device must be powerful enough to run the emulation.
- The emulator must be allowed to run sufficiently often.
The first point is rarely a problem, modern desktop and laptop computers are usually powerful enough. The most important aspect is a relatively fast CPU, and especially how fast a single thread can run.
The second point is more tricky. Power saving features and other resourcy-hungry applications can interfere with the emulation. Sometimes to the point of the emulation not running fast enough, but more often the result is stuttering and un-even emulation speed.
Why is stable performance so important?
In order to get smooth video output with stuttering (and without audio issues), the emulator must be to both emulate frames and display then on screen very quickly (typically 50 or 60 times per second). Modern games running on your system can typically account for small delays and uneven performance, but old computer systems ran at a fixed speed. So even quite small delays in generating and displaying a a video frame can cause noticable video stuttering (or crackling audio).
How to identify performance issues?
Write about the performance overlay (Mod+O).
Make sure the the emulator window has focus
On many systems, the application will get less run-time when it's not running in the foreground (meaning not having mouse and keyboard focus). So if you notice un-even performance, make sure that the emulator window is focused.
Running in full-screen might further ensure that the emulator gets enough resources.
Switch to a performance power profile
Avoid powersaving, this can throttle down your CPU/GPU making them run much slower than they can. Powersaving can also cause the emulator getting too little run-time, for example by pausing the emulator slightly, but long enough to cause stuttering.
If you have Linux; install the gamemoded daemon to allow the emulator to automatically switch to the performance CPU governor while the emulation is running.
Plug your computer to external power
Depending on your system, your computer may be throttled when running on battery alone. Switching to a performance power profile might alleviate this, or maybe not. You can try running with or without external power and see if it makes a difference.
Close other applications
Especially web browsers can use more CPU and resources than you might think, depending on the open tabs. On the other hand, if the applications are idle, they should not interfere.
If you believe other applications might interfere, you can try closing them and see if it helps. You can also use the task monitor of your operating system to see what applications are using resources.
Performance tips when insufficient host performance is the problem
You might recall running UAE on an old 200 Mhz Pentium processor, and wonder how it is possible that performance is even a topic in 2020! The emulation accuracy in modern UAE emulators is much better than it was 10-15 years ago, and this increased accuracy comes at the cost of requiring more powerful computers.
Emulating the Amiga 1200 is especially demanding, since the CPU is clocked twice as high as the CPU Amiga 500, and the emulator spends most of its time emulating the CPU.
Use the slowest Amiga needed for the job
Don’t emulate an Amiga 1200 if an Amiga 500 or an Amiga 600 will do. The CPU in Amiga 1200 is twice as fast as the one in Amiga 1000/500/500+/600, and you need a much more powerful computer to emulate A1200 at highest accuracy.
For example, many people use Amiga 1200 settings when running WHDLoad-installed games. But for most games, an Amiga 600 with Kickstart 2.0 will work equally well (or better), but will require a lot less resources to emulate.
Avoid using unnecessary features
FS-UAE requires more CPU and GPU performance when certain options are enabled. For example GPU performance will be affected when using pixelshaders.
Disabling video sync
FS-UAE will usually have higher performance with video sync turned off.
Reducing the color depth
FS-UAE can use less color depth in the internal video buffers as well as in the textures uploaded to the video card. For slower/older computers, this can give a nice speed boost (but should not matter for modern PCs):
video_format = rgb565
(This option will also automatically set texture_format = rgb5).
What would be the average CPU speed to shoot for to handle the higher end Amiga’s? etc from Apple 500 and up to CD32 with FS-UAE?
Good question. You should try to make sure to get at least a dual-core CPU. And, you are also most interested in the max performance of a *single thread* when looking at benchmark scores. This page is good for that: https://www.cpubenchmark.net/singleThread.html. I believe a score of about 800+ is sufficient to run FS-UAE with 68000 emulation cycle-exact at full speed in V-Sync mode. You probably need at least 1000+ score on that page for cycle-exact 68020 emulation (CD32). Maybe 1200+ to be really sure. But take this advice with a grain of salt, it’s based on possibly faulty memory. And the higher performance, the better, obviously 🙂 (More likely to run well with other background tasks running, etc).
I tested a bit on a cheap laptop with Intel Core i3-3217U @ 1.80GHz CPU. That one has a score of 901 on https://www.cpubenchmark.net/singleThread.html. It is just fast enough to run Aladdin AGA (Amiga 1200) with v-sync enabled. So something like this might be good enough, depending on how high expectations you have. But I do recommend something a bit more powerful 🙂
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Fsuae dev build from arch aur repository un acer aspire with pentium t4500 dual core and intel gma free driver the emulation is very slow, compton compositor is disabled and shader crt option enabled.
Other emulators run fast 🙁
The T4500 is a bit on the slow side for FS-UAE (https://www.cpubenchmark.net/singleThread.html). If things are *very* slow, please make sure you have hardware-accelerated OpenGL. You can also use Ctrl+F10 within FS-UAE to see (on graphs) if the problem is related to rendering or emulation. You can also see http://fs-uae.net/performance for performance tips.
Just curious… What sorts of things does “accuracy = -1” really do in the emulator?
Is it deprecated, or is it mostly harmless in well-behaved Amiga programs?
Hi, lowering accuracy to 0 disables cycle-exact (only for those models which are cycle-exact by default, for other models there are no difference between 1 and 0).
Lowering the accuracy to -1 sets the CPU to less compatible mode (no prefetch emulation), and enables immediate blits.
Is there any way to increase the loading time of the games?
There are several ways which can help, depending on the game:
– You can use F12+w (enable warp mode) to speed up the emulation (without) sound while the game is loading. Use F12+w once more to return to normal speed.
– Increase the speed of the floppy drive(s). See the docs for the option “floppy_drive_0_speed” (Note: this can break compatibility with some games).
– If the loading is CPU-bound, try using a faster Amiga model, for example an A1200 instead of A500/A600. But once again, this game break game compatibility too.
– Use the WHDLoad version of the game, which loads the game entirely from an emulated hard drive instead of floppies.
Hello, and thank you for this beautiful emulator engine!
1) I have some problem with the sound.
Generally the sound and the music is slow
For example in “Agony” is very bad, with terrible noises.
Generally in other games the sound and the music is slow or distorced.
During the disk chargement, the sound chrashing, or slows
During steps of loading diskettes, or during phases of very complex games (“AGONY”, Jim POwer, : the sound and the music gets worse and slows with buzz and heavy distortion and brutal noises.
I also noticed that the game sound gets worse when you hear the sound of the diskette drive at the same time with the music
The audio quality In Prince of Persia is better.
– In Ruff ‘n’ Tumble is discrete
in STARDUST is very good
in Speedball II is good
Sorry for my bad english.
I have Ubuntu 12.04 with Xubuntu and xfce
Kernel Linux 3.2.0-51-generic-pae
on small (2010) netbook with Intel Atom CPU N270 1.60 GHz x 2
in Configurations I run:
# accuracy = 0
# video_format = rgb565
# video_sync = off
2) VIDEO Performances:
– Some games are very fast, fluid and almost perfect: Stardust, Marble Madness, Speedball II, Alien Breed Special Edition, Chaos Engine, Exile;
-Ruff n Tumble is good
“Stardust” and “Exile”: very 100% perfect in game phases, (not in the intro main theme)
Others games are slow: sensible world of soccer, agony 🙁
and very slow: jim Power
Hi, sorry for late response. I think that your main problem is that your Intel Atom CPU N270 1.60 GHz is too slow to run FS-UAE at full speed. When the emulation cannot run at 100%, this will cause the audio to stutter. Some games are much more demanding to emulate then others, which explains why some games run fine while others do not. It depends how much the games “push” the Amiga.
On this benchmark page, Intel Atom N270 @ 1.60GHz has a score of 240 which is very low. I don’t know any exact minimum requirement for FS-UAE, but this is probably well below :-/
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