Displeased with the 32bit vs 64bit Fast As Possible

[Real_PhillBert]

I love the master, but this is pure ownage. Sorry Linus.

IDK. Linus clearly had a few facts wrong, but we all do that from time to time.

 

His rebuttal and reaction I found incredibly classy and I actually respect him even more after it. He got it twisted and handled it incredibly well. 

 

I for one, am impressed. Well done Linus.

[LinusTech]

I am a generalist, and when it comes to details, I will be the first to admit I don't know everything.

 

Almost every episode of Fast As Possible needs to be researched individually. I don't write them off the top of my head.

 

This has saved my bacon a lot of times, but it's also caused me to miss things a lot of times.

 

Just doing my best over here.

[flibberdipper]

IDK. Linus clearly had a few facts wrong, but we all do that from time to time.

 

His rebuttal and reaction I found incredibly classy and I actually respect him even more after it. He got it twisted and handled it incredibly well. 

 

I for one, am impressed. Well done Linus.

Did he bring up anything about the limit of numbers it can handle? There was a max money limit on GTA V due to 32-bit limitations. Think they fixed it though.

[ZiggyManSaad]

I am a generalist, and when it comes to details, I will be the first to admit I don't know everything.

 

Almost every episode of Fast As Possible needs to be researched individually. I don't write them off the top of my head.

 

This has saved my bacon a lot of times, but it's also caused me to miss things a lot of times.

 

Just doing my best over here.

I know it may take some time to do research on the topics of your Fast As Possible, why not get the help of the community? Get together a trusted band of members that know their shit, and create a special subforum that they only have access to to help you out. Just an idea.

[LinusTech]

I know it may take some time to do research on the topics of your Fast As Possible, why not get the help of the community? Get together a trusted band of members that know their shit, and create a special subforum that they only have access to to help you out. Just an idea.

 

 

Yes it's actually an idea we've been kicking around for a while.

[Jack.EXE]

Yes it's actually an idea we've been kicking around for a while.

 

This would be very useful, I can see how people like @Kuzma would be beneficial to FAP vids.

 

you should probably annotate this post of mine when you mention PAE, I did an in-depth study on it a while back.

http://linustechtips.com/main/topic/146022-32-bit-cpus-pae-4-gb-of-ram/

[The_Strict_Nein]

Did he bring up anything about the limit of numbers it can handle? There was a max money limit on GTA V due to 32-bit limitations. Think they fixed it though.

Or the max money stack stack in Runescape due to 32-bit Java

[Swndlr]

linus theres nothing more to say here other than boom roasted, still love you tho <3

[Vivilacqua1]

This would be very useful, I can see how people like @Kuzma would be beneficial to FAP vids.

 

you should probably annotate this post of mine when you mention PAE, I did an in-depth study on it a while back.

http://linustechtips.com/main/topic/146022-32-bit-cpus-pae-4-gb-of-ram/

fap videos.    lol     (i know what you meant though)

[PiFighter]

Because this video wasn't specifically about mobile platforms, Linus is/was technically correct!

Given the same code, compile for both 32-bit and 64-bit platform, you'll not see any performance benefits. (in fact, you may notice that 64-bit code performs worse because jumps are now 64 bits and causes program size to bloat, leading to poorer cache coherence and less efficiency) This is what we saw when we transitioned to 64-bit on desktop.

 

Apple's (ARM's ARMv8) is a bit of special case:  instead of keeping the same instructions and simply changing memory addresses to 64-bit, they actually introduced new set of instructions and wider registers that you can't access under 32-bit mode (Anand's article mentions it as well). That's why there's a performance delta. It wasn't the case of 32-bit vs 64-bit. It was a case of old architecture vs new architecture.

 

That said, when coded specifically for 64-bit, there CAN be performance benefit over 32-bit even under the same architecture. And even if your system has less than 4GB of RAM. The biggest benefit of 64-bit addressing, especially when your code shuffles a lot of data, is not so much the maximum amount of memory you can access, but the fact that virtual address space fragmentation no longer limits how much memory you can allocate! It probably sounds like gibberish to non-programmers, but it basically boils down to simpler memory management, cutting down on code size, thus the application running faster. Again, the program has to be designed for it. You won't be able to take this faster 64-bit application and recompile it for 32-bit and expect it to run fine.

 

And since PAE was mentioned... PAE in my opinion is just a glorified bank switching. Worse, actually, because programmers can't leverage it. It's nice that the OS can access more than 4GB of physical memory under PAE, but individual applications are still constrained to 4GB limit (or 3, depending on OS) and still subject to small address space and fragmentation that entails. It's basically worthless if you need to deal with large data.

 

 

EDIT: Although... the video is titled "32-bit vs 64-bit Computers & Phones" so maybe Linus was technically wrong...

I think I need to watch the video again to remember what was actually said.

 

EDIT2: Yeah seems like the video is mostly about mobile. For some bizarre reason I didn't remember it that way at all. Plus due to my reading comprehension failure, I just ended up reiterating what's already in the original post.  Please pretend that I never wrote the first 2 paragraphs.

[StingBull]

Did he bring up anything about the limit of numbers it can handle? There was a max money limit on GTA V due to 32-bit limitations. Think they fixed it though.

What, you can get more than $2147483647 on GTA 5?

[Tomiking]

What, you can get more than $2147483647 on GTA 5?

If you do all the correct stock investments before and after the assassination missions then you can easily finish the game with over 3 Billion (3 000 000 000) dollars between all the 3 characters and it also used to be possible to obtain properties for free that generate furhter income.

(I'm assuming that you were asking if a person could actually get that much by playing the game, and not talking about the actual software limitations or anything technical)

 

And as far as the video is concerned, I think Linus wanted the main point to be that people shouldn't decide between phones based on just the fact that one is 64 bit and the other is 32. Despite the mistakes that stand out to people like us on this forum as we are tech enthusiasts, I think the video still achieves what Linus and his team desired from it in terms of clearing things up for the average consumer.

Fast As Possibles aren't really aimed at people like the OP of this thread, while what you said is true and I appreciate the effort in you pointing it out, sometimes you have to consider that for the average person too much detail isn't always helpful, the same way that things you learn during chemistry lessons in high school aren't always necessarily 'true' but they allow everyone to have some basic understanding of what is going on.

[LucidMew]

Someone smarter than I should read the dolphin emulator's 32 bit obituary and use that as evidence. 

[flibberdipper]

What, you can get more than $2147483647 on GTA 5?

For a while after release you couldn't due to the 32-bit limitation deal, but now you can. It is possible to make a crap-ton of money like @Tomiking said though.

[cesrai]

bro, just chill.

Dude I'm sorry to tell you there won't be an iPhone 6 32GB gold I'm sorry.

[asquirrel]

*sigh* Linus is right, from a physics standpoint 64-bit is no faster than 32-bit. The reason 64-bit CPUs are objectively faster than 32-bit ones is because they have found faster ways to create the complex circuits for things like adders, dividers, shifters, etc. Put the same circuit in both 32 and 64 bit silicon implementations and on some tasks (multiplies mostly, some adds {specifically those where you must carry}) 32-bit would actually be faster, purely because there are fewer sequential steps to perform. Other instructions, like shifts, will be identical because they can be done completely in parallel.

 

Recompiling is needed, and debugging is needed because if you wrote your app in C, and did something like

long *numbers[10] = {1,2,3,4,5,6,7,8,9,10};

puts(numbers+4);

 

On 32-bit it would print out 4, on 64-bit it would print out 2. Why? Because the size of a long* changed. If you were smart enough to call sizeof(long*) instead of +4 then you would not see this issue. "People don't code that way!" They really do. I've seen it, within the past 2 years.

 

Also, if you are on a 64-bit CPU, then yes, running more things 64-bit on top of that should generally be faster than 32-bit. This should surprise no one; it'd be like being surprised that a V8 ran better with 8 cylinders firing instead of 4. Well no duh!

[LAwLz]

*sigh* Linus is right, from a physics standpoint 64-bit is no faster than 32-bit.

Eh, from a physics standpoint?

 

The reason 64-bit CPUs are objectively faster than 32-bit ones is because they have found faster ways to create the complex circuits for things like adders, dividers, shifters, etc. Put the same circuit in both 32 and 64 bit silicon implementations and on some tasks (multiplies mostly, some adds {specifically those where you must carry}) 32-bit would actually be faster, purely because there are fewer sequential steps to perform. Other instructions, like shifts, will be identical because they can be done completely in parallel.

[Citation needed]

Like I said in my post, the performance benefit of going to 64bit on ARM will mostly be from the more efficient instruction set, more general registers and so on.

However, there will be some benefits solely from having certain parts be 64bit. For example IPv6 headers are 64bit aligned so you will be able to process them more efficiently than on 32bit. Doesn't sound like a lot but being able to process every single packet a bit more efficiently when you get hundreds and maybe even thousands of them every second does quickly add up. Especially on a battery powered device which needs to be as efficient as possible.

 

Recompiling is needed, and debugging is needed because if you wrote your app in C, and did something like

long *numbers[10] = {1,2,3,4,5,6,7,8,9,10};

puts(numbers+4);

 

On 32-bit it would print out 4, on 64-bit it would print out 2. Why? Because the size of a long* changed. If you were smart enough to call sizeof(long*) instead of +4 then you would not see this issue. "People don't code that way!" They really do. I've seen it, within the past 2 years.

And that is why you should use sizeof(), and it's even more important if you're going to write cross platform applications. It's kind of irrelevant though because I wasn't really arguing against the point that you need to recompile and debug. I was arguing against the claim that it won't affect performance, because it will as you can see in the benchmarks I linked.

 

Also, if you are on a 64-bit CPU, then yes, running more things 64-bit on top of that should generally be faster than 32-bit. This should surprise no one; it'd be like being surprised that a V8 ran better with 8 cylinders firing instead of 4. Well no duh!

Well apparently it is a surprise to many, because I constantly see comments about how 64bit is useless and just marketing gimmick.

[Xorbot]

Well apparently it is a surprise to many, because I constantly see comments about how 64bit is useless and just marketing gimmick.

 

[TheUnknown]

Imagine the memory a 128 bit processors can handle and the speed benefits.

[BaSkA]

This would be very useful, I can see how people like @Kuzma would be beneficial to FAP vids.

 

OH YEAH, NOW WE'RE TALKING!

[Nicolas]

would be beneficial to FAP vids.

fap vids? I think those go on a different type of tube if you know what I mean

[xTurK]

OH YEAH, NOW WE'RE TALKING!

 

Why?

[BallGum]

Eh, from a physics standpoint?

[Citation needed]

Well apparently it is a surprise to many, because I constantly see comments about how 64bit is useless and just marketing gimmick.

It isn't a marketing gimmick, that's for sure, but it's definitely not some revolutionary, magical tech that makes your phone 10X faster, that's for sure. I think that's why many people dismiss it as a marketing gimmick, because of it being... 'Overhyped'.

Great post though, I remembered a discussion where you brought this up before anyways.

[Sanjeev]

You will get a performance boost with 64-bit if the applications have been optimized for 64-bit .A 64-bit OS can use 64-bit registers and ALU while a 32-bit bit OS has 32-bit registers and ALU .There are already many programs which have a 64-bit versions like WinRAR ,Chrome ,IE ,Handbrake etc.

 

And there are many who say 64-bit is only useful for accessing above 4 GB of RAM .Even though this one of the features it is not limited to only one

 

Watch these videos for more info

 

[Bouzoo]

Well said Chief Forum Scientist. Honestly I didn't think the improvements were that big. I knew they were there are were existing, but not that big. Never bothered to investigate.

Now see your influence as 60% of the forum starts with "We need 64 bit!". Well played.