Demystifying the SoC : What they are and why you should care

LeoRex

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810, 808, ARMv8, A53... ????

Processors are a hot item (har) at the moment... between the actual components themselves and the companies that build them, I can't remember a time where they've had a higher profile. This is meant for those who look at all these numbers and terms and get a bit crossed up. I hope I can help cut through the technical jargon and explain things so that you, too, can convince people that you know what you are talking about.

typing fast 1.jpg

What is a SoC?

It is short for "System on Chip". It's like Nachos... wait.... I'm just hungry.... OK... Most people are familiar with the concept of a computer processor. Remember the onslaught of "Intel Inside" and all that? A SoC is a computer processor on steroids and sent through an extensive cross training program. Smartphone manufacturers are put under some enormously challenging constraints; Make their phones fast, make their phones compact and make them energy efficient. To get there, chip makers cram as many components as possible on a single silicon (no, it's not made of corn) wafer or 'chip'; the main processor, graphics processor, system memory, radios (WiFi and mobile), etc. are all squished together on the same lump of silicon. It's like those REALLY good nachos that come with the chili and jalapenos... sorry... BRB.

OK.. consolidation like this sounds like a great idea... if you pick the right components and manufacture them the right way. Because once that choice is made, you're stuck with it since it is time and cost prohibitive to go in and start messing around with the chip manufacturing process once production has started. But if all is well, then everyone wins. We get phones that can do more with less power and are easier to design and manufacture.

What do they mean by A57 or A53?

Inside the SoC, you'll find the Central Processing Unit... the CPU... this is the brains of the operation and the heart of the SoC. These days, that CPU is much more than a single electronic brain, CPUs are now comprised of several processing cores capable of functioning independently. The cores that you find in many current generation phones are based on the Cortex-A architecture designed by ARM Holdings, with the chip makers themselves fabricating them. The core designs come in many different forms. Some, like the Cortex-A57, are quite powerful but use a lot of power while others (the Cortex-A53) sip electricity while they quietly take care of less processor intensive tasks. This pairing of high and low power cores is known as big.LITTLE and you'll find that most new SoCs going into the top of the line Android phones use big.LITTLE processors.

Why so many cores?

star-trek-enterprise-warp-core.jpg
Dude... the enterprise only needed 1 core...

One of the most common misconceptions with multi-core processors is that they are there to increase processing power. The real goal here isn't MOAR POWER!, it is actually less power (electrical power that is). If you have one giant, super-powerful core... that sucker has to stay powered up whether you are checking your email or playing Hearthstone. That big powerful core consumes a lot of energy no matter what you are doing. It's like using a dump truck to go pick up a gallon of milk at the store. Sure, it will get the job done, but it will do it in a horrendously inefficient way.

To solve this, designers replaced that single powerful core with a series of smaller, less powerful cores that can actually provide more overall processing power once they work in tandem. The advantage there is that when things get quiet, the phone can run on a small set of the available cores, even go so far as to bring all but one core completely offline. The aim is to get a CPU that is both powerful when you need it and energy efficient when you don't.

So what is all this about 20nm vs 14nm and why are we hearing about this now?

Long story short, the smaller and tighter they can pack in the transistors and little connections between them, the more efficient the chip... the more efficient the chip, the longer the phone will go on a charge. The structures in these chips are measured in nanometers. The naming of this technology node as "14 nm" came from the International Technology Roadmap for Semiconductors (ITRS (Read here for the gory, technical details).... Smaller, in this case, IS better... I'll leave it at that.

Samsung made a bit of a splash by being the first to market with a mobile SoC (the octa core Exynos 7420 in the Galaxy S6) that used a 14nm process. Qualcomm's Snapdragon 810 utilizes the same 8-core layout (4xA57 and 4xA53) as the Exynos 7420, but they used a 20nm fabrication process to build it. The result is a processor that produces a substantial amount of heat, so much so that OEMs are required to artificially slow the processor down to avoid overheating. While the Exynos is no cool cucumber in its own right, it doesn't suffer nearly the same thermal headaches.

But these headaches will pass as chipmakers move to processes that will be more thermally efficient. The next generation of Qualcomm chips after the 808/810 will be going to the newer processes, maybe even fabricated by Samsung (don't ask, that's a long story in and of itself). I chalk it up to growing pains from moving to the new 64bit ARMv8 architecture.

about that... What the deal with 32bit vs. 64bit? More bits are better, right?

Well, yes and no. By now, you might have seen material talking about how the new generation of chips is 64bit versus the older ones at 32bit. What is really going on is that chips are moving away from the ARMv7 architecture (which is 32bit) to the newer ARMv8 (64bit) architecture. This is actually a long time coming and the new architecture will bring with it several improvements.... better encryption, faster memory access, etc. But just because a chip is a 64bit chip doesn't make it faster. The new Moto E has a 64bit processor; the Snapdragon 410. But it is quite a bit slower than the older 32bit processors in the 800 family (800,801 and 805). The move to 64bit isn't necessarily about doing things faster, it's about doing more with less.

And even then, the software needs to be able to utilize it.... It wasn't until Android 5.0 that the operating system even supported 64 bit. And while 64 bit mobile apps are few and far between, this part isn't as critical since the move to 64bit has never really been about better-running apps, it was always about better running phones.

808 and 810??

Along with the 810, Qualcomm also introduced the Snapdragon 808 (which powers the LG G4). Like the 810, the 808 uses a series of Cortex-A57 and Cortex-A53 cores in a big.LITTLE configuration. But the 808 only has two of the high-power A57 cores that appear to lie at the heart of the 810 overheating issues. In benchmark tests, the 808 was able to run at full speed longer than the 810. So even though the 810 is more powerful than the 808, in real-world usage, the 808 may perform just as well (if not better at times). So there are a lot of eyes on which SoC we'll see in the upcoming launches from several major phone OEMs. Motorola, LG, OnePlus, Motorola are among many brands with new phones expected and it remains to be seen how the 810-equipt phones perform.

UPDATE: Well, turns out that Huawei and Google have figured out the magical, mystical incantations necessary to keep the 810 cool and happy. The Nexus 6P, powered by the Snapdragon 810, doesn't suffer from any of the thermally-sourced headaches of the phones from early in 2015. I should know, I bought one. :)

OK, smartypants... what about GHz? What do all those mean?

gigawatts.jpg
Settle down, there, Doc....

GHz stands for gigahertz... 1GHz is 1 billion times per second to be exact. That's the maximum clock speed of the processor and should not be confused with a processor's actual processing speed. A processor's clock speed is basically its drum beat. The faster the drum beats, the faster it can calculate and move around bits of data. But just because processor A has a higher clock speed than processor B doesn't automatically mean it is faster. Think of it this way; Superman and Spongebob are in a lifting contest. Spongebob can lift his box 20 times a minute but Superman only 10. Who is more powerful? Well, I forgot to mention that Superman is lifting the Queen Mary II and Spongebob a box of Kleenex. It isn't how quickly a processor does work, it is how much work that processor can do quickly.

But that's not the whole story. The speed of your processor is controlled by the Android OS's kernel...that's the low level bit that controls the hardware. It uses some code referred to as a governor to monitor your usage and increase or decrease the processor's speed accordingly. It is no different than your car's engine. You need more power, you stomp on the gas, your car accelerates. You want to go slower, you let off the gas. So when you are in Gmail just reading some emails, or taking a peek at your to-do list, the governor has most likely slowed things down to the phone's 'idle' clock speed to save power. Then once you open up Asphalt 8, your phone calls for flank speed, full steam ahead. It's called Dynamic Frequency Scaling...

Most phones have really conservative governor... they'll want to get that processor back down to it's 'idle' clock speed as quickly as possible in order to save power. Have you ever noticed that sometimes, if you've been looking at a window for a little bit, it kind of hiccups a bit before scrolling or going back to your homescreen? It seems to hesitate just a wee bit before getting smooth again? Well, while you were reading about Kylie and Kendal's graduation party, the governor slowed your processor speed down to idle. When you touched the screen, the governor hit go pedal to speed things up. The problem is that, like your car (again), it takes a little bit of time to go from 0 to 60. So while the phone speeds up, you might see it stutter a bit or lag a little.

Oh, one final note about processor speeds. Comparing speeds is ONLY useful when all things are kept equal. The Snapdragon 801 was really just a slightly upgraded version of the 800, and being a higher clock speed, you would expect greater performance (which would be correct). But once you start changing things... different core designs or switching from 32bit to 64bit, well, all bets are off... you can't use processor speed to gauge if SoC A is faster than SoC B.

So about that overheating phone...

Right. That governor also monitors the internal temperatures. As the processor is churning away, it is generating heat. If the phone starts to get too hot, the governor adjusts and slows the phone down. Depending on how much the processor has to be thottled, you may never really notice.

So what does this all mean to me?

It is like comparing an automotive engine from the muscle car era to one modern one. In 1970, you could pick up a Chevy Corvette with a brutish 460HP V8 engine.... Coincidentally, you can pick up a 2015 Corvette with a similarly brutish 460 V8.... Wow, we haven't really advanced at all, have we? But the 2015 version is rated to get close to 30mpg on the highway. The 1970 version? Well, you can get that kind of mileage... if you cut the engine and roll down a hill and the exhaust would most likely still kill every plant within 100 yards of the road.

Progress comes in many flavors. Starting with the Snapdragon 800 that we saw in the LG G2 and Nexus 5, mobile chips really came into their own in terms of performance. They were fast with the ability to push high-end graphics at full high definition resolutions. They were pretty much able to handle anything you threw at them. But now everyone has shifted their focus on to improving efficiency.... how that they've made mobile processors extremely fast, they want to make them extremely fast AND use a lot less power.
 
Last edited:

dennisharrison

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Feb 3, 2015
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810, 808, ARMv8, A53... ????

Processors are a hot item (har) at the moment... between the actual components themselves and the companies that build them, I can't remember a time where they've had a higher profile. This is meant for those who look at all these numbers and terms and get a bit crossed up. I hope I can help cut through the technical jargon and explain things so that you, too, can convince people that you know what you are talking about.

View attachment 189359

What is a SoC?

It is short for "System on Chip". It's like Nachos... wait.... I'm just hungry.... OK... Most people are familiar with the concept of a computer processor. Remember the onslaught of "Intel Inside" and all that? A SoC is a computer processor on steroids and sent through an extensive cross training program. Smartphone manufacturers are put under some enormously challenging constraints; Make their phones fast, make their phones compact and make them energy efficient. To get there, chip makers cram as many components as possible on a single silicon (no, it's not made of corn) wafer or 'chip'; the main processor, graphics processor, system memory, radios (WiFi and mobile), etc. are all squished together on the same lump of silicon. It's like those REALLY good nachos that come with the chili and jalapenos... sorry... BRB.

OK.. consolidation like this sounds like a great idea... if you pick the right components and manufacture them the right way. Because once that choice is made, you're stuck with it since it is time and cost prohibitive to go in and start messing around with the chip manufacturing process once production has started. But if all is well, then everyone wins. We get phones that can do more with less power and are easier to design and manufacture.

What do they mean by A57 or A53?

Inside the SoC, you'll find the Central Processing Unit... the CPU... this is the brains of the operation and the heart of the SoC. These days, that CPU is much more than a single electronic brain, CPUs are now comprised of several processing cores capable of functioning independently. The cores that you find in many current generation phones are based on the Cortex-A architecture designed by ARM Holdings, with the chip makers themselves fabricating them. The core designs come in many different forms. Some, like the Cortex-A57, are quite powerful but use a lot of power while others (the Cortex-A53) sip electricity while they quietly take care of less processor intensive tasks. This pairing of high and low power cores is known as big.LITTLE and you'll find that most new SoCs going into the top of the line Android phones use big.LITTLE processors.

Why so many cores?

View attachment 189842
Dude... the enterprise only needed 1 core...

One of the most common misconceptions with multi-core processors is that they are there to increase processing power. The real goal here isn't MOAR POWER!, it is actually less power (electrical power that is). If you have one giant, super-powerful core... that sucker has to stay powered up whether you are checking your email or playing Hearthstone. That big powerful core consumes a lot of energy no matter what you are doing. It's like using a dump truck to go pick up a gallon of milk at the store. Sure, it will get the job done, but it will do it in a horrendously inefficient way.

To solve this, designers replaced that single powerful core with a series of smaller, less powerful cores that can actually provide more overall processing power once they work in tandem. The advantage there is that when things get quiet, the phone can run on a small set of the available cores, even go so far as to bring all but one core completely offline. The aim is to get a CPU that is both powerful when you need it and energy efficient when you don't.

So what is all this about 20nm vs 14nm and why are we hearing about this now?

Long story short, the smaller and tighter they can pack in the transistors and little connections between them, the more efficient the chip... the more efficient the chip, the longer the phone will go on a charge. The structures in these chips are measured in nanometers. The naming of this technology node as "14 nm" came from the International Technology Roadmap for Semiconductors (ITRS (Read here for the gory, technical details).... Smaller, in this case, IS better... I'll leave it at that.

Samsung made a bit of a splash by being the first to market with a mobile SoC (the octa core Exynos 7420 in the Galaxy S6) that used a 14nm process. Qualcomm's Snapdragon 810 utilizes the same 8-core layout (4xA57 and 4xA53) as the Exynos 7420, but they used a 20nm fabrication process to build it. The result is a processor that produces a substantial amount of heat, so much so that OEMs are required to artificially slow the processor down to avoid overheating. While the Exynos is no cool cucumber in its own right, it doesn't suffer nearly the same thermal headaches.

But these headaches will pass as chipmakers move to processes that will be more thermally efficient. The next generation of Qualcomm chips after the 808/810 will be going to the newer processes, maybe even fabricated by Samsung (don't ask, that's a long story in and of itself). I chalk it up to growing pains from moving to the new 64bit ARMv8 architecture.

about that... What the deal with 32bit vs. 64bit? More bits are better, right?

Well, yes and no. By now, you might have seen material talking about how the new generation of chips is 64bit versus the older ones at 32bit. What is really going on is that chips are moving away from the ARMv7 architecture (which is 32bit) to the newer ARMv8 (64bit) architecture. This is actually a long time coming and the new architecture will bring with it several improvements.... better encryption, faster memory access, etc. But just because a chip is a 64bit chip doesn't make it faster. The new Moto E has a 64bit processor; the Snapdragon 410. But it is quite a bit slower than the older 32bit processors in the 800 family (800,801 and 805). The move to 64bit isn't necessarily about doing things faster, it's about doing more with less.

And even then, the software needs to be able to utilize it.... It wasn't until Android 5.0 that the operating system even supported 64 bit. And while 64 bit mobile apps are few and far between, this part isn't as critical since the move to 64bit has never really been about better-running apps, it was always about better running phones.

808 and 810??

Along with the 810, Qualcomm also introduced the Snapdragon 808 (which powers the LG G4). Like the 810, the 808 uses a series of Cortex-A57 and Cortex-A53 cores in a big.LITTLE configuration. But the 808 only has two of the high-power A57 cores that appear to lie at the heart of the 810 overheating issues. In benchmark tests, the 808 was able to run at full speed longer than the 810. So even though the 810 is more powerful than the 808, in real-world usage, the 808 may perform just as well (if not better at times). So there are a lot of eyes on which SoC we'll see in the upcoming launches from several major phone OEMs. Motorola, LG, OnePlus, Motorola are among many brands with new phones expected and it remains to be seen how the 810-equipt phones perform.

OK, smartypants... what about GHz? What do all those mean?

View attachment 189843
Settle down, there, Doc....

GHz stands for gigahertz... 1GHz is 1 billion times per second to be exact. That's the maximum clock speed of the processor and should not be confused with a processor's actual processing speed. A processor's clock speed is basically its drum beat. The faster the drum beats, the faster it can calculate and move around bits of data. But just because processor A has a higher clock speed than processor B doesn't automatically mean it is faster. Think of it this way; Superman and Spongebob are in a lifting contest. Spongebob can lift his box 20 times a minute but Superman only 10. Who is more powerful? Well, I forgot to mention that Superman is lifting the Queen Mary II and Spongebob a box of Kleenex. It isn't how quickly a processor does work, it is how much work that processor can do quickly.

But that's not the whole story. The speed of your processor is controlled by the Android OS's kernel...that's the low level bit that controls the hardware. It uses some code referred to as a governor to monitor your usage and increase or decrease the processor's speed accordingly. It is no different than your car's engine. You need more power, you stomp on the gas, your car accelerates. You want to go slower, you let off the gas. So when you are in Gmail just reading some emails, or taking a peek at your to-do list, the governor has most likely slowed things down to the phone's 'idle' clock speed to save power. Then once you open up Asphalt 8, your phone calls for flank speed, full steam ahead. It's called Dynamic Frequency Scaling...

Most phones have really conservative governor... they'll want to get that processor back down to it's 'idle' clock speed as quickly as possible in order to save power. Have you ever noticed that sometimes, if you've been looking at a window for a little bit, it kind of hiccups a bit before scrolling or going back to your homescreen? It seems to hesitate just a wee bit before getting smooth again? Well, while you were reading about Kylie and Kendal's graduation party, the governor slowed your processor speed down to idle. When you touched the screen, the governor hit go pedal to speed things up. The problem is that, like your car (again), it takes a little bit of time to go from 0 to 60. So while the phone speeds up, you might see it stutter a bit or lag a little.

So about that overheating phone...

Right. That governor also monitors the internal temperatures. As the processor is churning away, it is generating heat. If the phone starts to get too hot, the governor adjusts and slows the phone down. Depending on how much the processor has to be thottled, you may never really notice.

So what does this all mean to me?

It is like comparing an automotive engine from the muscle car era to one modern one. In 1970, you could pick up a Chevy Corvette with a brutish 460HP V8 engine.... Coincidentally, you can pick up a 2015 Corvette with a similarly brutish 460 V8.... Wow, we haven't really advanced at all, have we? But the 2015 version is rated to get close to 30mpg on the highway. The 1970 version? Well, you can get that kind of mileage... if you cut the engine and roll down a hill and the exhaust would most likely still kill every plant within 100 yards of the road.

Progress comes in many flavors. Starting with the Snapdragon 800 that we saw in the LG G2 and Nexus 5, mobile chips really came into their own in terms of performance. They were fast with the ability to push high-end graphics at full high definition resolutions. They were pretty much able to handle anything you threw at them. But now everyone has shifted their focus on to improving efficiency.... how that they've made mobile processors extremely fast, they want to make them extremely fast AND use a lot less power.

Just came across this. Bravo, Sir. Natural born (or, and, very practiced) teacher - excellent communication skills :)
 

thegreenbot

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No matter how hard I try I would always fail to understand this stuff. But man you said all that stuff so casually. I wish I could do that too but yeah I got the crux for sure. Thank you for this helpful information.
 

LeoRex

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Well, I'm a tech geek.... Love the stuff... and I always had an affinity for the little beepy doo-dads in my life. I get something and I must know everything about it... no menu unseen, no toggle unchecked. So talking about this stuff is actually fun for me. My wife, thankfully, just shakes her head and walks away and let's me go off, muttering under my breath about some silly topic.
 

Laura Knotek

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Well, I'm a tech geek.... Love the stuff... and I always had an affinity for the little beepy doo-dads in my life. I get something and I must know everything about it... no menu unseen, no toggle unchecked. So talking about this stuff is actually fun for me. My wife, thankfully, just shakes her head and walks away and let's me go off, muttering under my breath about some silly topic.

What's awesome is that you explained some really geeky stuff in a way that anyone can understand. :)
 

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