Displeased with the 32bit vs 64bit Fast As Possible

[LAwLz]

This post is just about the mobile side of things.

 

 

When I saw @LinusTech's video "32-bit vs 64-bit Computers & Phones as Fast As Possible" in my subscription box I thought "oh good, now I'll just be able to link to this video as soon as someone spreads misinformation about 64bit being useless oh phones". Then I watched the video and sad sadly disappointed.
 
 

[...] and finally application developers will need to at least recompile and debug their code just to achieve basic compatibility without taking advantage of any performance improvements.

Well, that's wrong. Sorry Linus. Just a simple recompile to AArch64 will in fact give your application a substantial performance increase (will vary from app to app).
Both you and I like Anand so I will link to his excellent comparison.

 
"B-b-but that is on different processors!" I hear some of you scream at me. No. That is the exact same processor, and the same program (nothing in the benchmarks were changed). The only difference is that when it was compiled, one was set to be 32bit, and one was set to be 64bit. That is the only difference. No tests except for the memory benchmark was changed.
So moving from 32bit to 64bit (or to be more specific, moving from Aarch32 to Aarch64) will give a pretty decent performance increase with next to no extra work. Hell, Android developers might not even have to change anything in their code because the application is not actually compiled by them, but rather it is compiled every time to launch it (or with ART, every time you update your phone). That's what Just-In-Time compilation means. The program is not compiled until just before it is needed.

 

Maybe the entire hardware and software industry will cooperate for a fast migration for the first time ever so that I can have huge performance gains, right? Anyone?

It is far more likely this time around actually. The "problem" with 64bit on desktops is that they want to maintain backwards compatibility. That won't be nearly as big of an issue on mobile. Microsoft, Apple and Google are not afraid to leave people who don't upgrade out in the cold. Apple has already moved the iPad and iPhone to 64bit. Let's say Apple will support all their phones for 4 years. That means that in about 3 years they won't support any 32bit hardware anymore.
All the first party apps are already 64bit. Microsoft has shown that they are willing to completely dump support even faster than 4 years, so I don't see them having a problem dictating that "okay, from now on everything has to be 64bit".
Android is kind of a mess so I have no idea how that might play out, but I am sure of one thing. The sooner we get 64bit, the sooner we will be 64bit only.

People change phones far more often than they change their desktop.
 
 

If you think a 64bit processor is faster then I am afraid you have bought into the hype my friends. For certain workloads, and nothing you're doing on your phone at the moment, there will be a benefit. But in most cases, what you're actually benefiting from is that a 64bit CPU will tend to have a newer, more robust design overall. With more registers, functional units memory bandwidth and all that other stuff.

Or maybe, you're the one who has jumped on the "64bit is useless because I don't understand it!" bandwagon that is trying to compare the transition to 64bit on mobile to the transition to 64bit on the desktop.
For certain workloads, many of which you're doing on a regular basis on your smartphone, the move to 64bit will bring a decent performance increase. Viewing photos, encryption (including but not limited to the one in the iPhone's finger print scanner, and SSL), compressing/decompressing archives and basically anything that uses floats will get a pretty good performance increase. I am pretty sure most people use apps that use those things every day.
 
Yes, you are correct in saying that it isn't because of the 64bit memory addressing space, but it is because of the move to ARMv8, which is 64bit. On phones the choice is ARMv7 instructions and 32bit, or ARMv8 instructions and 64bit.
I have no doubt in my mind that people will watch this video and think that the move to 64bit in phones is useless, when it will actually be a huge step forward. I guess you could say this video is throwing the baby out with the bath water.
 
Not to mention that we will soon have 4GB of RAM in phones and tablets and by that time we will need 64bit. And before anyone says "there is no reason for it", yes there is. iOS devices has major issues because of the low amount of RAM (1GB). Moving to 2GB would remove a lot of crashes and improve performance. The move to 3GB would increase performance on devices with high resolution screens (like the retina iPads and possibly the new, bigger iPhone) because you can dedicate more as VRAM. 4GB and beyond would help even more with the VRAM, and also be able to keep things cached for longer, and allow for more advanced apps. We are already seeing devices with proper multi tasking, like having multiple windows open at the same time on your tablet and that can benefit from more RAM as well.

 
 
 

To summarize I will quote Anand again.

The conclusion? There are definitely reasons outside of needing more memory to go 64-bit.

[Askew]

Linus doesn't normally swerve call outs, interested to see his response on this.

[Bogica]

I agree with you completely.

But on the RAM note, I wouldn't let them have 4GB RAM on a mobile device.

Why? Well the answer is simple: Software companies need to learn to write properly. My god, how the hell does a stupid ass app use over 200mb of RAM. It's shitty code I tell you. You probably have a ton of apps that use CPU time for NO GOOD REASON. Seriously, the quality of the coding has degraded so much it's making me sick. I get that some apps can't be rewrote because of backwards compatibility considering most of them run on Android 2.3 and 4.4. But then dump anything below Android 4.0. It's time to move forward but it's also time to start writing more efficient code.

[Murdoch]

I would file this under constructive criticism, good post Lawlz. The series should really be "as concise as possible", I've always thought the oversimplification in order to fit the format is of detriment to the content.

 

But I don't think I'm the intended audience.

[KemoKa]

We need to have Linus respond to this.

Not saying you're wrong at all, OP, 64-bit gives us substantial performance increases, but I really don't think that Linus is just pulling stuff out of his ass. Not when he works with computers for a living.

[Archangel1994]

Note: Please correct me on any mistakes I make.

 

It is far more likely this time around actually.

This issue is though that even if it takes 3-4 years (as you said) to give up the 32-bit support it's still a substantial amount of time before we move to 64-bit which still proves Linus' point. As of right now the 64-bit announcement has no real consumer-level value (Hell most probably don't even know what you gain from going 64-bit). I actually sincerely doubt it's even close to being more likely to have a quicker transition.

 

Microsoft has shown that they are willing to completely dump support even faster than 4 years

They might be willing but that does not mean they will do it outright and again. XP was already pretty darn bad IMO at the release of Windows 7. Also dumping support for an OS when there are literally 3 newer ones is a different ballpark than going for 32 to 64-bit.

 

People change phones far more often than they change their desktop

That means that people will pay a price premium for a 64-bit phone that will be under-utilized. Also by the time 64-bit will see widespread use then by that time there are better 64-bit phones which are most likely going to be with less of a price premium because they have been around for longer.

 

Not to mention that we will soon have 4GB of RAM in phones and tablets and by that time we will need 64bit. And before anyone says "there is no reason for it", yes there is.

While I do agree that the 1GB of VRAM is lacking there should really be no point whatsoever in putting more than 2-3GB of RAM in a phone. More RAM also means more power consumption (Vital aspect in phones, more so than in laptops/desktops), more heat and a higher price tag (and IMO they are too high as they are right now).

 

4GB and beyond would help even more with the VRAM, and also be able to keep things cached for longer, and allow for more advanced apps. We are already seeing devices with proper multi tasking, like having multiple windows open at the same time on your tablet and that can benefit from more RAM as well.

Truthfully if you need that much RAM and you need to multitask that much you would be so much better off with a laptop and apps that are "advanced" should also be advanced enough to be written to require less RAM, therefore eliminating the need for very high amounts of RAM in a phone.

[ShadowCaptain]

SNIP

 

No word of a lie, when I saw this video I immediately thought, I bet Lawlz has something to say about this, because I remember you and me having the exact same discussion a few months back, where everyone was saying that 64bit is only useful for having more RAM

 

And here you are

[AlwaysFSX]

17 users, you got the forum's attention.

[WolfDeville]

Haven't watched the vid yet. Please tell me this isn't true lol

[Archangel1994]

17 users, you got the forum's attention.

Well he just implied that a Linus Video was disappointing/bad. Of course you draw attention with that .

[LAwLz]

But on the RAM note, I wouldn't let them have 4GB RAM on a mobile device.

Why? Well the answer is simple: Software companies need to learn to write properly. My god, how the hell does a stupid ass app use over 200mb of RAM. It's shitty code I tell you. You probably have a ton of apps that use CPU time for NO GOOD REASON. Seriously, the quality of the coding has degraded so much it's making me sick. I get that some apps can't be rewrote because of backwards compatibility considering most of them run on Android 2.3 and 4.4. But then dump anything below Android 4.0. It's time to move forward but it's also time to start writing more efficient code.

Oh don't get me started on software bloat... I agree that developers need to put more effort into optimization, but in the end there is only so much optimization you can do. My usage is probably not the same as the average Joe but yesterday when I was visiting one of my favorite websites I ended up having 12 tabs in my browser open. Each tab had about 20 images in it. Each image was just a fairly small thumbnail but it still end up being a decent amount of RAM. If I had wanted to multitask, as well as keep stuff in cache for a decent amount of time, as well as having a decent amount of VRAM for my 2560x1600 screen I could probably have benefited from 4GB of RAM or maybe even more.

I think better hardware AND better software is the way forward.

 

 

 

This issue is though that even if it takes 3-4 years (as you said) to give up the 32-bit support it's still a substantial amount of time before we move to 64-bit which still proves Linus' point. As of right now the 64-bit announcement has no real consumer-level value (Hell most probably don't even know what you gain from going 64-bit). I actually sincerely doubt it's even close to being more likely to have a quicker transition.

Well that's just before it's completely unsupported on newer software. During those few years we will see 32bit and 64bit applications coexist. For example on the iPhone Apple has moved all the first party apps to 64bit, and if your phone supports the 64bit version of the app in the app store you will download that automatically.

I think there is a value to consumers as well. Higher performance is always good, especially if it's seamless to the users, and requires very little effort from the developers.

 

They might be willing but that does not mean they will do it outright and again. XP was already pretty darn bad IMO at the release of Windows 7. Also dumping support for an OS when there are literally 3 newer ones is a different ballpark than going for 32 to 64-bit.

Well I was talking about phone OSes. Not a single WP7 handset got updated to WP8. If Microsoft decided that WP9 would be 64bit only, they could do that and all of a sudden all WP9 software would have to be 64bit.

 

That means that people will pay a price premium for a 64-bit phone that will be under-utilized. Also by the time 64-bit will see widespread use then by that time there are better 64-bit phones which are most likely going to be with less of a price premium because they have been around for longer.

Not really under-utilized since a lot of everyday tasks benefit from it, but they won't get the same benefit as if all software was 64bit, yes.

It probably won't be that big of a price premium though. These SoCs are really cheap. We aren't talking about 200-300 dollar CPUs. We are talking about maybe a 10 dollar increase in the BOM for the manufacturers. Besides, there will be cheap SoCs with 64bit support.

The Desire 510 is by no means a premium device, but it has 64bit compatible hardware in it. The newly announced Desire 820 also has a 64bit compatible SoC.

Qualcomm has a complete lineup of ARMv8 SoCs which covers all price brackets.

 

While I do agree that the 1GB of VRAM is lacking there should really be no point whatsoever in putting more than 2-3GB of RAM in a phone. More RAM also means more power consumption (Vital aspect in phones, more so than in laptops/desktops), more heat and a higher price tag (and IMO they are too high as they are right now).

Well we are already seeing the benefits of having more than 2GB of RAM in phones (more VRAM helps quite a lot at 1080p and above). With the move to 64bit we will also see the RAM usage go up slightly. The power and heat increase is negligible, especially with the move to LPDDR4. It's probably not even 1mW for 1-2GB of extra RAM 8for comparison, the Galaxy S 5's 1080p display uses over 800mW by itself). The price difference is pretty negligible as well if you're looking at purely BOM cost. The cost difference between 2GB and 3GB is 1 dollar.

 

Truthfully if you need that much RAM and you need to multitask that much you would be so much better off with a laptop and apps that are "advanced" should also be advanced enough to be written to require less RAM, therefore eliminating the need for very high amounts of RAM in a phone.

I don't think "just use a different device" is a valid reason for halting progress on phones and tablets.

[Real_PhillBert]

Interesting. I am more than a little interested in seeing what Linus' response is to this.

[Norwegiantweaker]

cant wait to see linus response to this 

[Archangel1994]

Well that's just before it's completely unsupported on newer software. During those few years we will see 32bit and 64bit applications coexist. For example on the iPhone Apple has moved all the first party apps to 64bit, and if your phone supports the 64bit version of the app in the app store you will download that automatically.

I think there is a value to consumers as well. Higher performance is always good, especially if it's seamless to the users, and requires very little effort from the developers.

While the transition may be seamless, Linus is correct on the fact that the actual performance increase will not be noticed by your day-to-day user or the performance increase is plain not significant enough at this point. While higher performance is good there is no point in upgrading if you go from 5 second execution time to 4 second (Making a really pulled out of my sleeve example here). 

 

I don't think "just use a different device" is a valid reason for halting progress on phones and tablets.

I think it's a completely valid reason to be fair (Up to a certain point, I do not accept halting forever but delayed I'm perfectly fine with). Specific platforms have specific needs in mind. A phone is not intended for heavy multitasking or advanced apps and a desktop is not intended to be easy to use for mobility. If I need to heavily multitask that I require 7 apps open (and use them all at the same time) or have 25 internet tabs with images then a laptop is a much more suitable option (They don't need to be bulky, Macbooks are a prime example here). However I must note that this is mostly personal preference.

 

Well I was talking about phone OSes. Not a single WP7 handset got updated to WP8. If Microsoft decided that WP9 would be 64bit only, they could do that and all of a sudden all WP9 software would have to be 64bit.

If windows decides to go 64-bit only with WP9 ahead of the rest I expect them to drop to "last place" in terms of choice because others will still support both. That would just be bad from a marketing point of view/

 

 

Well we are already seeing the benefits of having more than 2GB of RAM in phones (more VRAM helps quite a lot at 1080p and above). With the move to 64bit we will also see the RAM usage go up slightly. The power and heat increase is negligible, especially with the move to LPDDR4. It's probably not even 1mW for 1-2GB of extra RAM 8for comparison, the Galaxy S 5's 1080p display uses over 800mW by itself). The price difference is pretty negligible as well if you're looking at purely BOM cost. The cost difference between 2GB and 3GB is 1 dollar.

I did not realize that LPDDR4 was already out and used frequently. Did I completely miss it or are you assuming a scenario where LPDDR4 is already out?

 

The other argument I submit to your counter-argument.

[nokturrduk84]

It's time to leave some ancient technologies & 32bit is one of them. 32bit OS? Really? Who's still using it? How many users here use 32bit system? I doubt any financial average person has more than 4gb & it's pretty budget friendly to build 4gb+ RAM system nowdays. We just need to leave this 32bit systems, there is no necessity of them anymore.

[terrytek]

snip

bro, just chill.

[GoodBytes]

Very well said.

And for those that don't know why compiling code for a 64-bit version, without code modification, leads to higher performance. This is the compiler itself at work that can optimize the programed code, making the program, now, use the 64-bit processors new operation codes it supports and longer instructions reducing processor workload. Basically, the compiler will do a lot of the work for the developer, and transform his or her code to be more 64-bit CPU optimized. To put it briefly.

[GoodBytes]

While the transition may be seamless, Linus is correct on the fact that the actual performance increase will not be noticed by your day-to-day user or the performance increase is plain not significant enough at this point. While higher performance is good there is no point in upgrading if you go from 5 second execution time to 4 second (Making a really pulled out of my sleeve example here).

True, but remember that the ARM processor in a phone is low powered. So it's easily pushed to level where 64-bit CPU could make a difference, potentially.

[79wjd]

But on the RAM note, I wouldn't let them have 4GB RAM on a mobile device.

Why? Well the answer is simple: Software companies need to learn to write properly. My god, how the hell does a stupid ass app use over 200mb of RAM. It's shitty code I tell you. You probably have a ton of apps that use CPU time for NO GOOD REASON. Seriously, the quality of the coding has degraded so much it's making me sick. I get that some apps can't be rewrote because of backwards compatibility considering most of them run on Android 2.3 and 4.4. But then dump anything below Android 4.0. It's time to move forward but it's also time to start writing more efficient code.

Well, part of the issue is the memory and processing power is virtually dirt cheap nowadays--certainly cheaper than reworking and optimizing code. 

 

Well written and properly optimized code is a great thing to have....but is it worth the extra time and money that could be spent on pushing the app itself further, or working on something better.

[Captain_Slow]

I'm sorry, but for this sort of under-the-hood technical thing, I trust Anand over Linus.

[Bogica]

Oh don't get me started on software bloat... I agree that developers need to put more effort into optimization, but in the end there is only so much optimization you can do. My usage is probably not the same as the average Joe but yesterday when I was visiting one of my favorite websites I ended up having 12 tabs in my browser open. Each tab had about 20 images in it. Each image was just a fairly small thumbnail but it still end up being a decent amount of RAM. If I had wanted to multitask, as well as keep stuff in cache for a decent amount of time, as well as having a decent amount of VRAM for my 2560x1600 screen I could probably have benefited from 4GB of RAM or maybe even more.

I think better hardware AND better software is the way forward.

Agreed. But unfortunately the side effect of devices having more RAM is sloppy coding as developers think there is no need to optimize when there's so much RAM. So we NEED to FORCE them to write better. It will be much more time consuming, but everyone will be glad they did it. But then again, maybe it's a thing, if everything worked so well then we would feel no need to purchase new and better hardware.

 

You sir, I like you, as you raise valid arguments and back them up with fact. (no homo)

[LAwLz]

While the transition may be seamless, Linus is correct on the fact that the actual performance increase will not be noticed by your day-to-day user or the performance increase is plain not significant enough at this point. While higher performance is good there is no point in upgrading if you go from 5 second execution time to 4 second (Making a really pulled out of my sleeve example here).

Well I listed a few things a lot of people do all the time on their phones, and even if a photo renders 20% faster isn't that noticeable of a difference, many small savings can become a big saving.

In the case of AES encryption we could see 8 minute encryption time drop to 1 minute. That's very significant. It can potentially save battery life as well, since you need far less instructions (about a 30% reduction in instructions needed for the same tasks) and the faster a task is done the faster the CPU can go into idle.

 

I think it's a completely valid reason to be fair (Up to a certain point, I do not accept halting forever but delayed I'm perfectly fine with). Specific platforms have specific needs in mind. A phone is not intended for heavy multitasking or advanced apps and a desktop is not intended to be easy to use for mobility. If I need to heavily multitask that I require 7 apps open (and use them all at the same time) or have 25 internet tabs with images then a laptop is a much more suitable option (They don't need to be bulky, Macbooks are a prime example here). However I must note that this is mostly personal preference.

Well I have to agree with you on the phone front. However, I disagree with you when it comes to tablets. On 10" and bigger tablets (see Galaxy Pro series) you have more than enough room for multitasking.

 

If windows decides to go 64-bit only with WP9 ahead of the rest I expect them to drop to "last place" in terms of choice because others will still support both. That would just be bad from a marketing point of view/

Yeah dropping support for all handsets on the market again (like they did with WP7 -> WP8) would be a pretty big blow to their image.

The thing is though, you don't really have to support both. There isn't really any good reason for it. Like I said before Qualcomm already has a full lineup of 64bit chips (not all of them are released yet like the 810, but they are on their way) and I don't really see any reason to stick with 32bit if they cost about the same. In the low/mid range spectrum we aren't even talking 10 dollars, we might be talking 2 or 3 dollars. That's a pretty small amount considering the big performance difference there will be between a last gen, low/mid range CPU and a brand new, 64bit compatible CPU. So for the handset manufacturers it wouldn't make that much of a difference.

Users would probably be pissed though.

 

I did not realize that LPDDR4 was already out and used frequently. Did I completely miss it or are you assuming a scenario where LPDDR4 is already out?

Well no Android phone with a 64bit CPU is out either. Snapdragon 810 (the high end 64bit CPU) will support LPDDR4.

The comment about LPDDR4 was not even my main argument, but rather a "it's a really really small issue now, and it will get even smaller in the future" kind of deal. Even IF it was a big deal today (which it isn't) it would be even less of a deal when we actually start seeing 64bit chips in Android and Windows handsets.

 

 

 

bro, just chill.

I am chill.

 

 

 

Agreed. But unfortunately the side effect of devices having more RAM is sloppy coding as developers think there is no need to optimize when there's so much RAM. So we NEED to FORCE them to write better. It will be much more time consuming, but everyone will be glad they did it. But then again, maybe it's a thing, if everything worked so well then we would feel no need to purchase new and better hardware.

 

You sir, I like you, as you raise valid arguments and back them up with fact. (no homo)

I like you too sir. Totally homo.

[LinusTech]

Awesome post, and a great point about the performance improvements achieved in some workloads simply by recompiling. I've added an annotation to the video and a link in the description to this post. Thanks for pointing that out to me. It was a clear miss.

 

As for performance in real world applcations, yes, it could result in an improvement in encryption performance from 8s to 1s, but when is the last time something on your phone took 8s to encrypt? I maintain that for normal people this is the sort of thing that is simply not a huge deal, and shouldn't factor into their decision to buy a phone.

 

As for the ecosystem, you make a good point about Apple's transition being likely to be smooth (it was also smoother on the desktop - something I should have pointed out), but I have less faith than you in Microsoft's ability to execute the transition (they already have an app quantity problem on the store. Do you really think they're going to enforce a 64-bit only policy?) and based on what I've seen of Android so far I"ll be floored if it's not a complete gong show...

 

As for the conclusion of the video, I still don't think 64-bit is a reason to buy a phone. At all. It's a necessary step forward, and soon you won't have a choice anyway, so that's something I should have mentioned.

[babbaj]

Awesome post, and a great point about the performance improvements achieved in some workloads simply by recompiling. I've added an annotation to the video and a link in the description to this post. Thanks for pointing that out to me. It was a clear miss.

 

As for performance in real world applcations, yes, it could result in an improvement in encryption performance from 8s to 1s, but when is the last time something on your phone took 8s to encrypt? I maintain that for normal people this is the sort of thing that is simply not a huge deal, and shouldn't factor into their decision to buy a phone.

 

As for the ecosystem, you make a good point about Apple's transition being likely to be smooth (it was also smoother on the desktop - something I should have pointed out), but I have less faith than you in Microsoft's ability to execute the transition (they already have an app quantity problem on the store. Do you really think they're going to enforce a 64-bit only policy?) and based on what I've seen of Android so far I"ll be floored if it's not a complete gong show...

 

As for the conclusion of the video, I still don't think 64-bit is a reason to buy a phone. At all. It's a necessary step forward, and soon you won't have a choice anyway, so that's something I should have mentioned.

gg

[flibberdipper]

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