How much GPU is used by PPSSPP?

[Danyal Zia]

In most emulators, the CPU speed seems to be the vital thing for performance of emulators as compared to GPU. But, I have read in PPSSPP forum that GPU seems to be important in terms of performance. Now, can someone tell me how much GPU is used by PPSSPP? Can we precisely say it in percentage ratio, such as 60% GPU 40% CPU? In case of PC, even old ATI Radeon X800 and X300 seems to be very good in performance in PPSSPP. Is VRAM more important or GPU clock is more important?

Edit: I mistakenly rated it as 1 star and now I can't change it. Sigh...

[Henrik]

It varies enormously from game to game, and from GPU to GPU. No way to give a generic percentage.

[Danyal Zia]

(06-07-2013 01:02 PM)Henrik Wrote:  It varies enormously from game to game, and from GPU to GPU. No way to give a generic percentage.

Thanks for reply! But, Is it true that almost most rendering on higher resolution is done by GPU? While, at 1x most rendering seems be done by CPU? My way to check the power of GPU is to evaluate VPS at higher resolutions, if VPS remains same (in unlimited) inspite of higher resolution then I think GPU is good enough for PPSSPP. I think it makes sense. I was just wondering if VRAM is more important for higher resolutions or just GPU clock?

[Donel]

Use gpu-z to check this. It gives a percentage to GPU load.

[xsacha]

Basically you need a CPU fast enough to generate 60 frames (run the CPU loop) for that game-- usually quite a weak CPU.
Then you need a GPU fast enough to render those 60 frames -- usually a fairly decent GPU but depends on the game.

You wouldn't associate percentages with them. It's more a threshold thing.

You can get 60 VPS and 0 FPS with no GPU, for eg.
You can get 0 VPS (and hence 0 FPS) with no CPU, for eg.

A lot of emulators don't use the GPU at all for the emulation (like shaders). Basically PS1 and everything weaker.

[Danyal Zia]

(06-07-2013 05:42 PM)Donel Wrote:  Use gpu-z to check this. It gives a percentage to GPU load.

I've just checked it through GPU-Z. It seems that in lower resolutions, GPU load is negligible (about 5-10%) and emulation is mostly done by CPU. But, in higher resolutions, GPU load seems to increases (about 50-60%). I've checked this with Castlevania Dracula X Chronicles. Now my question is: Are xBRZ texture scaling done by GPU emulation as shader implementation? As I can see the increase in load of GPU when I increase amount of texture scaling (from 2x to 4x)

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(06-09-2013 05:01 AM)xsacha Wrote:  Basically you need a CPU fast enough to generate 60 frames (run the CPU loop) for that game-- usually quite a weak CPU.
Then you need a GPU fast enough to render those 60 frames -- usually a fairly decent GPU but depends on the game.

You wouldn't associate percentages with them. It's more a threshold thing.

You can get 60 VPS and 0 FPS with no GPU, for eg.
You can get 0 VPS (and hence 0 FPS) with no CPU, for eg.

A lot of emulators don't use the GPU at all for the emulation (like shaders). Basically PS1 and everything weaker.

How can it produce 60 VPS if there are no frames at all?! Through frameskipping, right? Many emulators such as Desmume (Nintendo DS emulator) don't use GPU at all that's why they are too slow. Using filters there make it more slow as it seems filtering is done by CPU too! PPSSPP is damn fast that's why I was wondering if it's secret of performance is behind the fact that some operations in PPSSPP is done by GPU.

[xsacha]

The CPU generates the frames. The GPU doesn't need to render them. That's frameskipping, yes.
When most people say they get 60 VPS, it's because of this.

[Squall Leonhart]

frameskipping usually implies not generating them on the cpu.

[Henrik]

Yeah it does skip the CPU work of sending the OpenGL commands, which can actually be very expensive by itself on mobile.

[Danyal Zia]

Thanks for all the replies! Now, we can conclude by saying that if frameskipping helps to run at 60 VPS it means that the performance of emulator is limited by GPU in that particular device, since GPU isn't fast enough to render all those 60 frames at a time. In the end, it has proven that GPU surely has an impact on performance of emulator.