CPU vs GPU

Guilherme · 01-16-2017, 11:57 PM #1

Hey guys! I'd like know what's the actual problem of current android phone, is it the CPU or the GPU? I can see we have strong GPUs, like Adreno 530, with 400-500 GFLOPs, which is not bad, I guess it's enough to run GameCube games at least on native resolution, but it doesn't happen, so I think we don't have a CPU powerful enough, isn't it?

Grey1213 · (This post was last modified: 01-17-2017, 12:09 AM by Grey1213.)

The cpu is the main bottleneck that could do with more performance. The GPU has major issues too, not performance related but to do with poor gpu driver support (presumably functions the gpu should be able to do, but isn't supported to do these things because of Qualcomm or ARM).

Guilherme · 01-17-2017, 12:32 AM #3

I understand. Anyway, it'll take some time until games get playable on Android phones, we'll need a very powerful hardware or a better driver optimization. Thank you!

**mbc07** · (This post was last modified: 01-17-2017, 01:14 PM by mbc07.)

That's not entirely true, our ARM64 JIT is pretty decent from what I've heard, and since the NVIDIA Shield TV can already run some lightweight games at full speed, I bet the issue is mostly on the mobile GPUs side. Different from Shield TV, they don't expose a full desktop OpenGL profile, so we have to use either Vulkan or Open GL ES, which actually are not in a good shape on mobile devices. It's not a case of weak GPU, it's a case of veeery bad drivers, it was much worse in the past at the point they barely rendered anything, nowadays most mobile GPU drivers display correct (or close to correct) graphics, but remain utterly slow due to missing or not correctly implemented GL ES/Vulkan features.

TL;DR with decent GPU drivers the current Android devices would perform better (obviously not full speed, but certainly better)...

olihey · 01-17-2017, 08:29 PM #5

(01-17-2017, 01:12 PM)Jhonn Wrote: our ARM64 JIT is pretty decent from what I've heard, and since the NVIDIA Shield TV can already run some lightweight games at full speed, I bet the issue is mostly on the mobile GPUs side.

Unfortunately it's fully the CPU lagging the Nvidia Shield TV. I did some (un-scientifc) tests (Soulcalibur II & How to train your dragon I) on my Nvidia Shield TV and it's purely the CPU preventing an good experience. The frame rate for both games is the same no matter if I use 1x native or 3x plus anti aliasing.

Even when I use the NULL renderer I can here the sound shuttering.

To bad, I was really hoping to get my WII replaced with the Nvidia Shield TV.

**degasus** · 01-17-2017, 08:45 PM #6

(01-17-2017, 08:29 PM)olihey Wrote: Even when I use the NULL renderer I can here the sound shuttering.

In the logcat (available by ADB), you can still see the framerates. And indeed, the NVIDIA GL driver is by far the best compared to all other mobile ones.

olihey · 01-17-2017, 09:05 PM #7

(01-17-2017, 08:45 PM)degasus Wrote: In the logcat (available by ADB), you can still see the framerates. And indeed, the NVIDIA GL driver is by far the best compared to all other mobile ones.

Didn't know that, awesome Smile

So, here is "How to train your dragon I" with OpenGL, 3x native and 2x Anti-Aliasing

Code:
01-17 12:01:28.165 3916-4241/? I/DolphinEmuNative: JITARM64 DC | OpenGL | HLE | FPS: 32 - VPS: 32 - 54%

01-17 12:01:29.168 3916-4241/? I/DolphinEmuNative: JITARM64 DC | OpenGL | HLE | FPS: 32 - VPS: 32 - 53%

01-17 12:01:30.169 3916-4241/? I/DolphinEmuNative: JITARM64 DC | OpenGL | HLE | FPS: 33 - VPS: 33 - 55%

01-17 12:01:31.182 3916-4241/? I/DolphinEmuNative: JITARM64 DC | OpenGL | HLE | FPS: 32 - VPS: 32 - 53%

01-17 12:01:32.207 3916-4241/? I/DolphinEmuNative: JITARM64 DC | OpenGL | HLE | FPS: 30 - VPS: 30 - 50%

And here the same game with NULL renderer

Code:
1-17 11:59:38.510 3916-4010/? I/DolphinEmuNative: JITARM64 DC | Null | HLE | FPS: 38 - VPS: 38 - 64%

01-17 11:59:39.511 3916-4010/? I/DolphinEmuNative: JITARM64 DC | Null | HLE | FPS: 38 - VPS: 38 - 63%

01-17 11:59:40.512 3916-4010/? I/DolphinEmuNative: JITARM64 DC | Null | HLE | FPS: 36 - VPS: 36 - 60%

01-17 11:59:41.514 3916-4010/? I/DolphinEmuNative: JITARM64 DC | Null | HLE | FPS: 38 - VPS: 38 - 63%

01-17 11:59:42.521 3916-4010/? I/DolphinEmuNative: JITARM64 DC | Null | HLE | FPS: 38 - VPS: 38 - 63%

01-17 11:59:43.523 3916-4010/? I/DolphinEmuNative: JITARM64 DC | Null | HLE | FPS: 38 - VPS: 38 - 63%

So, it's purely the CPU that's lagging. But I guess a 100% speed up in CPU emulation might be a big task Wink

Grey1213 · 01-17-2017, 10:08 PM #8

(01-17-2017, 09:05 PM)olihey Wrote: Didn't know that, awesome

Yeah, iirc the shield TV is only clocked at 2.0GHz, and the CPU is basically two generations old. So apart from the lack of throttling, the performance over the latest smartphone should be entirely GPU based. On geekbench 4 the CPU scores 1500 on single core, which is less than most sd820 devices.

Guilherme · 01-17-2017, 11:10 PM #9

Well, it's to expect NVIDIA Tegra GPUs will have a good performance, they are based on desktop architecture, and the PC GPUs has no driver issue or something running Dolphin. But any mobile CPU is not fast enough to run everything at full speed, anyway, I already expected it, I just want to know what's the main problem currently.
I know Dolphin is not too GPU demanding, I tested it on a Pentium G2030 and Intel HD Graphics, the GPU handle it fine, but the CPU is always 100%.

**degasus** · 01-18-2017, 12:17 AM **#10**

Dolphin doesn't depend on a good GPU performance. But emulation yields a strange GPU usage with tons of small buffer updates. This hits a very slow path on all drivers which don't support coherent mapping. Bad luck, QC implemented it in their ES3.2 drivers, nobody else on the mobile did so. We're we're talking about 1-2fps to 10-20 fps. Next issue are state validation. This is still CPU overhead, and uses quite a big amount of the available time. But the effect is a lot smaller.