Will 64-bit mobile processors matter for PPSSPP performance?

[shan109]

Please disregard this question if it is already asked in another thread...

Earlier, Apple has released the first "64-bit" mobile phone processor for its Iphone, and from now on it is expected for future android mobile processors to have 64-bit architecture, however I'm wondering how this will affect the speed/ overall performance of PPSSPP??

Will we gain MASSIVE speed/performance boosts on PPSSPP from these upcoming 64-bit mobile processors??

Any opinion??

Regards,

[VIRGIN KLM]

I guess the difference will be the same as x86/x64 on Intel/AMD processors but in this case in a manner of mobile processor speeds.
So if the gain was little on Intel/AMD then you can expect simmilar results (and less) on 64 bit ARM based processors.
I don't really get why there should be 64bit processors yet on mobile devices. It's not like 32bit ones have even came near to reaching their limmits. It was an "innovation" by Apple just for the record that they did it, like to have their name on the list of who did it first and nothing else. The thing is that it is quite some time actualy possible (the use of 64bit processors on mobile devices) but it would and will offer nothing to mobile devices for the time being and that includes near future aswell. So Apple didn't think performance or "think ahead" when they used it, they did it just because they wanted to brag about something that makes no sense to people that have zero computing education (aka typical Apple marketing trick). So if people expect anything from the 32bit/64bit swap on their iPhones and that only then I can tell you that the previous processor will offer better results if you'd overclock it just by ~50Hz up which is equal to wasting your money and time.

[StriderVM]

The 64-Bit is pointless. Generally.

For example, is the 64-bit version of Windows twice as fast as the 32-Bit version? It will generally be the same for Smartphones. Developers will not be bothered to use 64-bit programming as the problems far outweight the benefits. Such as device compability. Not every Apple user will have the same phone after all.

[shan109]

OK, thank you for your explanations/opinions

[[Unknown]]

On Intel, there are some decent tradeoffs:

On x64 Intel:
* Pointers are bigger (and thus slower). There's supposedly a 32-bit-pointer ABI being discussed which helps a lot here.
* There are more hardware registers, so you don't have to waste time juggling. Faster.
* Sometimes video drivers (even same card) are pretty different, maybe better, maybe worse.
* You can address a lot more ram (PPSSPP doesn't use that much ram.)
* SSE is about the same.

In the end, it's often a wash. For me, x64 is sometimes faster, sometimes slower.

However, on ARM, I'm pretty sure it doesn't increase the number of registers, and afaik it kills some condition codes on some instructions. The biggest benefit is probably largest registers. I don't know the ABI, so it may also be slower due to pointer sizes.

I wouldn't expect any huge gains from ARM 64 personally. I guess the main point is more addressable RAM.

-[Unknown]

[Henrik]

[Unknown], for once you're actually at least partly wrong

http://www.arm.com/files/downloads/ARMv8...ecture.pdf

ARM64 doubles the amount of GPR registers, which means that we can probably almost entirely ditch the regalloc and use a static mapping instead.

It has an improved NEON unit, also with more registers.

In addition, we can do the same memory mirror trick we do on x86-64, saving one instruction per memory access.

We will have to write a separate new JIT though as ARM64 is quite different from ARM32.

[[Unknown]]

Heh, I'm very often at least partly wrong. Well, that's cool, I guess we'll see how much better it is.

Graphic drivers probably matter more though, of course.

-[Unknown]

[Tamagotchi]

(09-11-2013 02:03 AM)VIRGIN KLM Wrote:  I guess the difference will be the same as x86/x64 on Intel/AMD processors but in this case in a manner of mobile processor speeds.
So if the gain was little on Intel/AMD then you can expect simmilar results (and less) on 64 bit ARM based processors.
I don't really get why there should be 64bit processors yet on mobile devices. It's not like 32bit ones have even came near to reaching their limmits. It was an "innovation" by Apple just for the record that they did it, like to have their name on the list of who did it first and nothing else. The thing is that it is quite some time actualy possible (the use of 64bit processors on mobile devices) but it would and will offer nothing to mobile devices for the time being and that includes near future aswell. So Apple didn't think performance or "think ahead" when they used it, they did it just because they wanted to brag about something that makes no sense to people that have zero computing education (aka typical Apple marketing trick). So if people expect anything from the 32bit/64bit swap on their iPhones and that only then I can tell you that the previous processor will offer better results if you'd overclock it just by ~50Hz up which is equal to wasting your money and time.

Is there a way to overclock the iphone 5 ?

[VIRGIN KLM]

Nope, it was a theory, iOS kernel does not allow such thing.

[Henrik]

The full ARMv8 architecture reference manual was released yesterday:

http://infocenter.arm.com/help/index.jsp...index.html

(you need to register a free account to get it)

The brand new instruction encoding is super clean and it seems to be a very very good ISA in every way we care about. Hard to guess the performance improvement but writing a JIT for this will be a joy.

My guess is that Android Kitkat will be released for these 64-bit CPUs, waiting with anticipation...

[tntbandicoot]

Sir Henrik, you're friggin' cool hermano.

[VIRGIN KLM]

(09-12-2013 07:34 AM)Henrik Wrote:  The full ARMv8 architecture reference manual was released yesterday:

http://infocenter.arm.com/help/index.jsp...index.html

(you need to register a free account to get it)

The brand new instruction encoding is super clean and it seems to be a very very good ISA in every way we care about. Hard to guess the performance improvement but writing a JIT for this will be a joy.

My guess is that Android Kitkat will be released for these 64-bit CPUs, waiting with anticipation...

+1

[Henrik]

This is what I'm talking about:

http://androidandme.com/2013/09/news/sam...ssor-game/

Not really a confirmation for 64-bit kitkat, but hey.

[stodag]

I wonder how ppsspp will run on these bad boys.

I would like one but I'm broke as a joke.