How does PPSSPP perform so well?

[sandbox424]

I know I have decent hardware (i5 4690k @4.5ghz, 16gb RAM, gtx 960) but I can't see how it performs so well. I mean compared to pcsx2, which isn't bad by any means, it seems like it doesn't stress my PC much at all. I run it at 10x native resolution (damn near 5k) and 5x texture upscaling. I can't make it run poorly even if i tried (which I have.) I run games such as MGS Peace Walker and FFVII Crisis Core in turbo mode and they get constant frame rates of 300% and 200% respectively. It seems like they could exceed those speeds, but it's as if they're locked. My GPU is only mid level but it isn't chugging along or anything. Are PSP games just easy to emulate? I know the 2 God of War titles are a bit difficult to get full speed on, but not impossible. (Ghost of Sparta runs flawlessly for me, even without the prevent fps from exceeding 60 setting turned on. In fact it refuses to exceed 60 fps anyways. turbo doesn't seem to work on it, but i don't really care.)
I know the minimum requirements are dual core CPU @2.0ghz, 2gb RAM, and I guess any GPU supporting openGL 2.0. So what would recommended specs be like? I tried searching for some but it doesn't look like there is a list of recommended specs.

[[Unknown]]

There are many reasons why PPSSPP performs well:

1. A lot of time has been spent optimizing it for much weaker devices than yours.

We've spent a lot of time trying to make it run on weaker devices, like mobile, which means a desktop like yours is a wonderland for it. Of course, there's always more improvements to make.

2. The PSP is just the right balance between modern and ancient.

Older devices than the PSP (including very much the PS2) make it a lot easier for games to rely on hardware quirks. These have to be emulated, which can make things a lot slower.

Newer devices are more complex, and tend to have a lot more concurrency. In some ways this is good, but emulating it accurately enough that games work properly again comes with a speed penalty.

3. The base resolution is pretty low.

PSP games render 42.5% as many pixels as PS2 games. What this means is that 10x PSP is less than half as demanding as 10x PS2 would be on your hardware.

4. The PSP is a mobile device.

On a console, whether you use 100% of the processing power or 50%, there's no real difference. On a mobile device, using 50% means the battery lasts longer.

This doesn't always mean games are more optimized, but sometimes they are. PSP games actually usually run 25% slower than on a PS2 (although the PSP is capable of 10% faster than the PS2), which means emulating it is at least 25% less demanding on the CPU level, usually.

5. We use some magic tricks.

Some of the things we do to optimize memory access, reduce jit codesize, etc. have been very carefully designed. Not all of them are even possible in a PS2 emulator due to differences in the hardware. The pcsx2 team know about the tricks that could work for PS2 emulation, but don't think they'll help much.

6. The PS2 is darn complicated.

The PS2 is much more complicated than the PS1, Wii, and I assume the Xbox. It's arguably more complicated than the PS3. Its hardware does a lot of tricky things, so where the PSP is definitely on the easier to emulate side, the PS2 is on the harder to emulate side. You've picked the system that makes PPSSPP look the best in comparison.


As far as recommended specs - it can vary heavily by what game you're trying to run.

I think a GeForce 750 Ti and 3.2 Ghz i5 would be enough to have a good experience in pretty much any game at nice settings. That being said, for 5x texture scaling, a 4.0+ Ghz i5/i7 is definitely more ideal. As for RAM, PPSSPP itself doesn't need much so even 4GB or less would still be recommended.

For a phone, there's really no device that will give you an awesome experience with high quality settings, but with modest settings things should work fine on the latest powerful devices out now - 2.0+ Ghz CPU, Tegra K1 or X1 / Adreno 4xx / Mali-T6xx / PowerVR-6xxx.

-[Unknown]

[sandbox424]

(08-28-2015 03:59 AM)[Unknown] Wrote:  There are many reasons why PPSSPP performs well:

1. A lot of time has been spent optimizing it for much weaker devices than yours.
-[Unknown]

Well that is just fantastic. Keep up the great work. I wish PCSX2 would try those tricks to make emulation run better, but I guess it's too much work for them.

[vnctdj]

(08-28-2015 03:59 AM)[Unknown] Wrote:  [...]

Very informative reply, thanks