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Could you please diagnose my bottleneck?
06-06-2017, 10:45 AM (This post was last modified: 06-06-2017 10:47 AM by whgang99.)
Post: #1
Could you please diagnose my bottleneck?
Hello, I enjoy psp games on my phone with ppsspp. My phone is fast enough to play many games at playable level, but not fast enough to be frame-drops-free, so I play games with some degree of frame skipping. And recently, I got a question, exactly which part of my phone is being a bottleneck?
For example, on one scene, the game runs at 17fps out of 30 with frame skip disabled on my phone, regardless of internal resolution. And if I enable frame skips on that scene, game can run at full speed with frame rate dropping to a single digit, again, regardless of internal resolution. Does this mean the bottleneck is my CPU or GPU? Or you can't determine what's a bottle just by this? Also, my phone's processors are Qualcomm Snapdragon msm8974 2.3GHz quad-core and Adreno 330. (Which are known to be powerful, but unsuited for PPSSPP) (I have little experience in PC gaming, so I can't diagnose what these symptoms mean. I heard if game performance doesn't get better by lowering options, it's a CPU bottleneck but I don't know if it can be applied to emulators...)
I'd appreciate if you explain me what are the symptoms when CPU/GPU is bottlenecking an emulator. Thanks in advance.
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06-06-2017, 12:24 PM (This post was last modified: 06-06-2017 12:24 PM by Asferot.)
Post: #2
RE: Could you please diagnose my bottleneck?
The basic idea is simple.
If your game runs slow on lowest graphical settings and does not change speed if you change them to higher setting, it means your CPU is the bottleneck.

If your game runs bad with lowest settings and gets noticeably slower on higher setting then it is GPU.

Also. When I say higher setting I mean a small change, not 10x render resolution full AA and all other settings cranked up to 11.

Everything is Hitsuzen!
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06-06-2017, 03:28 PM
Post: #3
RE: Could you please diagnose my bottleneck?
Honestly for a phone it does not matter. The same is also true for most laptops, tablets and some tv boxes. If you can not change your CPU and/or your GPU then it wont matter which is the issue since the only way to get better performance at the settings you currently use is to replace the device.

That said for most emulators the speed is determined by the CPU unless the GPU is just not good enough to run the emulator at all. If you remove all enhancements (increased resolution [still kinda cpu dependent], AA, AF, Shaders, ect.) and nothing changes then that is the best speed your CPU with that device can handle for that emulated game.

For native PC games it is almost always reversed where the GPU determines the speed once the CPU is powerful enough to run the game without holding the CPU back. To test native PC games you just raise the resolution (putting more strain on the GPU) and if no performance decrease is evident then your CPU is just not good enough to let your GPU go at it's best.
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06-06-2017, 04:07 PM
Post: #4
RE: Could you please diagnose my bottleneck?
Thank you both. So It means CPU is the problem... (Kinda surprising that the bottleneck was CPU even on my laptop with integrated graphics card - it showed same symptoms.)
But then, could you please answer another question?
I use many emulators on my phone and the most demanding ones are definately DraStic (with high resolution) and PPSSPP. And for both of them, CPU should be the bottleneck. (DraStic is known to use software rendering, which means it relies on CPU, right?) But even though they both seem to be utilizing my phone's full power(DraStic frame drops, PPSSPP slows down), DraStic uses significantly greater battery compared to PPSSPP. Is this then supposed to be related to multi-core usage or something?
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06-06-2017, 07:29 PM
Post: #5
RE: Could you please diagnose my bottleneck?
DraStic high res mode is really designed for and on Exophases laptop, He kind of always said it might work on highend devices but probably not always well. Drastic only uses your GPU to display the output from the emulator and to do shaders all the calculations are done in software.

But one thing that could be happening on your device is
1. Your manufacturer has an agressive power savings scheme in how the governor is set so your device is not using the full power of your chip.
2. Your device does not have enough cooling to allow your chip to run at full power and the chip is downclocking to save itself from damage.

These are the 2 most common issues phones have with emulators

As for your laptop it depends on your processor, but ypu also might want to make sure that windows power savings plan is set to performance not power savings, but it depends on the processor.
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06-06-2017, 09:56 PM
Post: #6
RE: Could you please diagnose my bottleneck?
Thank you. I guess it's quite a complex matter.
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06-07-2017, 12:48 AM
Post: #7
RE: Could you please diagnose my bottleneck?
Is your phone a Nexus 5? That configuration sounds familar.

The Nexus 5 (and possibly other phones) has a firmware bug that limits it to 58/60 fps. This means in games that attempt to run 60 fps, you will need to enable frameskip. This isn't the 17 fps issue, but may help explain other issues.

It's worth noting: PPSSPP tends to be bottlenecked by GPU, or importantly by GPU drivers, more often than other emulators. And based on frameskip, I actually think you are not CPU bottlenecked.

The reason is simple: PPSSPP never skips CPU emulation. Frameskip only skips drawing. If increasing frameskip makes PPSSPP run faster, then you're dealing with something rendering related.

There are lots of things that can impact it as noted - but what game is this, specifically? Another thing to consider is that some PSP games use tricky rendering techniques (you might be surprised the lengths to which some games go to attain outlines around objects, for example), and it could be that this particular scene is doing something that is just slow on modern devices.

There are many rendering techniques which were used on the PSP - a device launched in 2004 - that hardware vendors stopped supporting, because there were better techniques that could be made even faster. But this means those old techniques are now very slow on modern hardware - just no modern game would actually use them.

If your laptop is using an Intel GPU, you may also be better off switching to the Direct3D 11 backend, which may perform better.

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06-07-2017, 09:42 PM
Post: #8
RE: Could you please diagnose my bottleneck?
Thanks for your reply, but I think the main problem is very simple: my device is slow. My phone is LG Vu 3, which uses the same CPU/GPU with Nexus 5, but the firmware bug seems to be not my case. My game is KHBbS, which runs at decent speed in many scenes but slows down dramatically if there are effects, like splashing water, on the screen.
I believe the real solution is buying a better PC.
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06-07-2017, 10:49 PM (This post was last modified: 06-07-2017 10:50 PM by The Phoenix.)
Post: #9
RE: Could you please diagnose my bottleneck?
(06-07-2017 09:42 PM)whgang99 Wrote:  Thanks for your reply, but I think the main problem is very simple: my device is slow. My phone is LG Vu 3, which uses the same CPU/GPU with Nexus 5, but the firmware bug seems to be not my case. My game is KHBbS, which runs at decent speed in many scenes but slows down dramatically if there are effects, like splashing water, on the screen.
I believe the real solution is buying a better PC.
Hi there whgang99,

Have tried the following settings, on the Graphics tab, under Performance:
1xPSP
Same as rendering resolution
Hardware resolution: ticked
Software Skinning: ticked
Lazy texture caching: ticked
Retain changed textures: untucked
Disable slower effects: ticked
Spline/Bezier curves quality: Low.

If that doesn't work, try enabling Frameskip to 1 x or 2 x, this combined with settings above should get your performance up.
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06-13-2017, 08:06 PM
Post: #10
RE: Could you please diagnose my bottleneck?
One thing that bother me is that PPSSPP works with OpenGL ES 2.0, if implement a newer OpenGL, it wound't improve the performance on Android devices? PSP has simple graphics, a modern GPU wouldn't have great problems to render them since it's well optimized, and we have powerful GPUs nowadays, from 100 to 600 GFLOPs (I don't know about Adreno 540, I belive it has 700+ GFLOPs). Could a dev tell if the a newer OpenGL would improve the performance or not?

Anyway, CPU is still a great problem for PPSSPP running with OpenGL, I have a huge CPU usage in heavy games like God of War Chains of Olympus and Midnight Club 3 with Core i5 3470 (reaches up to 70% at one core and up to 40% overall usage).

Phones: Galaxy S10 Lite and Redmi Note 6 Pro

PC: Core i5 3470/8GB RAM/GTX 660 2GB/Windows 10 Pro x64
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06-16-2017, 08:05 AM
Post: #11
RE: Could you please diagnose my bottleneck?
I'm sorry for replying late...
The Phoenix, thank you for your tips, but as I mentioned, changing resolution doesn't change my performances at all and the only way to help is allowing frame skips, which results playable speeds&fps's on many games but many heavy games skip too much frames to be playable. I'm thinking of changing my phone&laptop sometime later this year, and that would likely solve my problem.
Again, thanks for your reply, and sorry I forgot checking this thread for too long.
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06-16-2017, 01:55 PM
Post: #12
RE: Could you please diagnose my bottleneck?
@whgang99 did you already try to change emulated PSP CPU clock in system settings? I lower clock can improve the emulation speed at cost of some FPS (depending on the game, you don't lose too much FPS), anyway it's better than frameskiping.

Phones: Galaxy S10 Lite and Redmi Note 6 Pro

PC: Core i5 3470/8GB RAM/GTX 660 2GB/Windows 10 Pro x64
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06-18-2017, 05:27 AM
Post: #13
RE: Could you please diagnose my bottleneck?
Yes, I did. And in many cases it helped little if at all, or with artifacts.
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06-18-2017, 06:35 PM
Post: #14
RE: Could you please diagnose my bottleneck?
Does your phone perform well in android games? Are you sure that you're not dealing with thermal throttling?

Ryzen 5 1600 @3.8Ghz
Sapphire Nitro+ RX480 @1.4Ghz
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06-18-2017, 09:21 PM
Post: #15
RE: Could you please diagnose my bottleneck?
Most other games and emulators perform well, including DraStic's hi-res mode. And about thermal throttling, that I don't know really well. I haven't rooted my device, which means I can't mess with it anyways.
I heard that Snapdragons are bad on PPSSPP, so I think I'm in an extremely normal situation.
Where I heard it:
https://www.reddit.com/r/EmulationOnAndr...ragon_810/
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