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Option to underclock PSP?
06-05-2013, 09:13 PM
Post: #1
Option to underclock PSP?
Would an option to underclock the CPU help give faster speeds on Android? (or any other platform)? Just a thought.
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06-05-2013, 09:18 PM
Post: #2
RE: Option to underclock PSP?
underclock or overclock?, some people says it gives better performance when you overclock the CPU on android, but you have to have a special kernel to do that, what device do you have?
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06-05-2013, 09:21 PM
Post: #3
RE: Option to underclock PSP?
He means the virtual PSP's CPU, not the actual device.

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06-06-2013, 12:07 AM
Post: #4
RE: Option to underclock PSP?
Yeah, the PSP CPU that PPSSPP emulates.
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06-06-2013, 03:56 AM
Post: #5
RE: Option to underclock PSP?
We could try it, but it's very likely to just break games. Anyway, most games are limited by the GPU side of things, meaning even less CPU usage won't improve VPS much.

-[Unknown]
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06-06-2013, 09:45 AM
Post: #6
RE: Option to underclock PSP?
I have a similar question...in Kingdom Hearts: Birth by Sleep (and Final Mix) there's two options in the config menu. One allows you to increase the CPU speed (presumably so you can get better performance/load times at the expense of battery) and the other increases the colour depth from 16bits to 32bits. Do these options actually do anything?
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06-06-2013, 10:47 AM (This post was last modified: 06-06-2013 10:51 AM by VIRGIN KLM.)
Post: #7
RE: Option to underclock PSP?
(06-06-2013 03:56 AM)[Unknown] Wrote:  We could try it, but it's very likely to just break games. Anyway, most games are limited by the GPU side of things, meaning even less CPU usage won't improve VPS much.

-[Unknown]
I think on the case of PSP that's not exactly true. Just try on a real PSP using CWCheats to underclock CPU/GPU gradualy by a little to alot and have enabled the FPS and CPU usage on screen. The results are rather impressive. Just a sometimes even halfing the frequencies doesn't seem to affect FPS at all and yet the CPU usage goes to half. (Not with all games but atleast with the majority). Also it would be a perfect/nearly flawless substitute to frameskipping. Also I'm 100% sure that all games with no exception can run at 266/133 instead of PPSSPP's default 333/166 so there wouldn't be any game specific inability/restriction.
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06-06-2013, 11:27 AM
Post: #8
RE: Option to underclock PSP?
Most PSP games runs perfectly fine at 222mhz. The only game I can think of that has occasional frame drops without the CPU being set to 333mhz is Little Big Planet.
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06-06-2013, 01:57 PM
Post: #9
RE: Option to underclock PSP?
(06-06-2013 10:47 AM)VIRGIN KLM Wrote:  The results are rather impressive. Just a sometimes even halfing the frequencies doesn't seem to affect FPS at all and yet the CPU usage goes to half.

Exactly. The problem is, when the emulator is spending most of its time in the GPU, reducing the CPU usage isn't gonna do much. The FPS won't change, it won't reduce, so it will still be spending just as much time on the GPU.

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06-06-2013, 04:28 PM (This post was last modified: 06-06-2013 04:29 PM by solarmystic.)
Post: #10
RE: Option to underclock PSP?
(06-06-2013 01:57 PM)[Unknown] Wrote:  
(06-06-2013 10:47 AM)VIRGIN KLM Wrote:  The results are rather impressive. Just a sometimes even halfing the frequencies doesn't seem to affect FPS at all and yet the CPU usage goes to half.

Exactly. The problem is, when the emulator is spending most of its time in the GPU, reducing the CPU usage isn't gonna do much. The FPS won't change, it won't reduce, so it will still be spending just as much time on the GPU.

-[Unknown]

There quite a few games which spend a lot of time in the CPU for the emulator, like the Tekken games and Soul Calibur.

I reckon VIRGIN's suggestion could make for a nice speed hack on the side for those CPU heavy games.

PPSSPP Modern Testbed:-
Intel Core i5 4690K @ 4.0 GHz
NVIDIA Geforce GTX 760 2GB GDDR5 VRAM @ 1138/6500 Mhz
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PPSSPP Ancient Testing Rig:-
Intel Core 2 Duo T9550 @ 2.8GHz
ATI Mobility Radeon 4670 1GB GDDR3 VRAM @ 843/882 MHz
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06-12-2013, 12:08 AM (This post was last modified: 06-12-2013 12:12 AM by xsacha.)
Post: #11
RE: Option to underclock PSP?
(06-06-2013 04:28 PM)solarmystic Wrote:  There quite a few games which spend a lot of time in the CPU for the emulator, like the Tekken games and Soul Calibur.

I reckon VIRGIN's suggestion could make for a nice speed hack on the side for those CPU heavy games.

Soul Calibur and Tekken series are heavily GPU orientated here.
I can easily get 60 VPS (and rather jerky gameplay) with frameskip and 1.5GHz CPU.
Remove frameskip and I'm getting about 20 FPS.

Sure, 1.5GHz is a lot. But my GPU ain't bad either.

I think lowering the 333MHz clock to 222MHz in Tekken will have the adverse effect. It will choke the game and slow it down further.
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06-12-2013, 12:11 AM
Post: #12
RE: Option to underclock PSP?
Cycle skipping like PCSX2 uses may be of use for the android formfactor.
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06-12-2013, 01:53 PM
Post: #13
RE: Option to underclock PSP?
PCSX2 is a different beast. PPSSPP skips all idle cycles already.
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06-12-2013, 02:21 PM (This post was last modified: 06-12-2013 02:22 PM by VIRGIN KLM.)
Post: #14
RE: Option to underclock PSP?
(06-12-2013 12:08 AM)xsacha Wrote:  Soul Calibur and Tekken series are heavily GPU orientated here.
I can easily get 60 VPS (and rather jerky gameplay) with frameskip and 1.5GHz CPU.
Remove frameskip and I'm getting about 20 FPS.

Sure, 1.5GHz is a lot. But my GPU ain't bad either.

I think lowering the 333MHz clock to 222MHz in Tekken will have the adverse effect. It will choke the game and slow it down further.
Have you tried it? Because it doesn't, even at lower values than 222MHz.
Don't think of them like how they react to underclock settings/speedhacks in PCSX2 (speedhack is working as a slowdown instead of a speedhack).
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06-12-2013, 08:20 PM (This post was last modified: 06-12-2013 08:20 PM by TheDax.)
Post: #15
RE: Option to underclock PSP?
PSP games don't really get buggy or crash when the CPU speed is below the optimal level; they act more like PC games: they just stutter and/or sound funny when you do it/if you go too low, so I don't think it would hurt to have such a feature added.

In fact, I've just finished working on such a feature; it's pretty trivial to implement, and it's off by default.
https://github.com/hrydgard/ppsspp/pull/2235

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How to ask useful questions: https://web.archive.org/web/20110214010944/http://support.microsoft.com/kb/555375
I'm not Dark_Alex, nor do I claim to be. Our nicknames are merely coincidence.
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