Lesson 3: All About Processor
Basic info on Processor
Processor is the topic we are going to discuss today, you might have heard a lot of terms like, 2.1Ghz, clock speed, 28nm, SoC, Octa Core, etc.which are all related to the processor. So, read along and you shall make meaning of these terms and understand what these really are.
Introduction
A processor executes what you want your smartphone to do. Early mobile phones were essentially cousins of traditional landline telephones. Smartphones, however, are portable computers that happen to have telephone capabilities built in. Underneath that amazing touchscreen display is a full-fledged computer, responsible for telling your apps how to function, your GPS how to get you home and you who to call on the telephone. The processor is the brains of the operation.
To understand mobile processors we need to first understand what is a processor which is often referred to as Central processing unit (CPU)
A CPU typically contains Arithmetic logic Unit (ALU), Control Unit (CU), Memory Unit and Input/Output Unit I/O. These units coordinate with each other and do the processing. You might ask what is a process? Any program under execution is a process, suppose you do a basic mathematic operaion 3+2 , you will use a calculator which is a program, so the processor recieves the data from the I/O i.e. from the keyboard or touchscreen, and then the ALU calculates the data and gives us the inforamtion i.e. 5.
The form, design and implementation of CPUs have changed over the course of their history, but their fundamental operation remains almost unchanged. Principal components of a CPU include the arithmetic logic unit (ALU) that performs arithmetic and logic operations, processor registers that supply operands to the ALU and store the results of ALU operations, and a control unit that fetches instructions from memory and "executes" them by directing the coordinated operations of the ALU, registers and other components.
SoC
SoC is short for System on a Chip, an integrated circuit that combines all the primary components of a computer into a single chip. Most modern CPUs are microprocessors, meaning they are contained on a single integrated circuit (IC) chip. An IC that contains a CPU may also contain memory, peripheral interfaces, and other components of a computer; such integrated devices are variously called microcontrollers or systems on a chip (SoC). Some computers employ a multi-core processor, which is a single chip containing two or more CPUs called "cores"; in that context, single chips are sometimes referred to as "sockets". Array processors or vector processors have multiple processors that operate in parallel, with no unit considered central.
Think of your CPU, graphics card, memory controller and other components all rolled into a single chip, that’s essentially an SoC. Unlike the CPU component in an SoC that’s primarily supplied by ARM, the graphics portion is manufactured by multiple vendors which gives companies the flexibility to pick and choose which GPU goes best with the CPU in their SoC.
While back in the day, the primary job of the graphics card was rendering 3D images and displaying them on the screen, today GPUs are used for much more than just playing games and are as crucial as the CPU, if not more. Today’s operating systems like Google’s Lollipop rely heavily on the GPU since the interface and all the animations are rendered on the graphics chip, which is how you’re able to get the buttery smooth transition effects. It also comes in handy when watching HD videos. Just like its PC component, a graphics chip essentially has more cores than a CPU thereby allowing it distribute the load better and leaving the CPU free for other tasks.
Ex: Snapdragon is a system on a chip (SoC) product family by Qualcomm, targeted to low-power mobile devices such as smartphones, tablets, and smartbooks. Depending on the model, the SoCs can include up to eight CPU cores, a graphics core, audio/video decoders, and modems for wireless and cellular networks.
Snapdragon doesn’t use the ARM architecture and has designed core Scorpion processor based on ARMv7 instruction set with features similar to ARM Cortex-A8. The first generation of Snapdragon processor with 65nm transistors was embedded in Nexus One and HTC HD2. Snapdragon has now come-up with 45nm technology Snapdragon chips in HTC Desire HD, Thunderbolt. More transistors mean improved performance.
What is a core ?
It’s an element found in the main processor that reads and executes instructions. Devices began with a single-core processor, but engineers created more powerful devices by including more cores in one device. That led to dual-core devices. Soon there were quad-core processors (as in four cores), and now there are hexa- (six) and octa-core (eight) smartphones and tablets.
The more cores, the faster they can divvy up the work you’re asking the phone to do. That means multiple cores make your experience snappy: Apps load quickly. You can capture high-quality photos or HD video and then browse through your collection without pause. Animations and videos play smoothly without stuttering. Games don’t get bogged down. There are exceptions, but generally the more cores the better the performance.
An octa-core processor is faster than a quad-core processor only when it’s running an app that takes advantage of its abilities or when you’re multitasking. For example, one core may be at work on your web browsing while another is standing by. A call comes in, and the second core gets to work. Both your web browsing and your phone call continue without a hitch, but not necessarily twice as fast.
Number of cores in the CPU plays a crucial role in defining its performance. If your mobile phone has a dual-core processor, it will be faster than a single core processor phone because the work will be divided between both the cores. But, dual-core devices consume more battery.
Lets use a example The Snapdragon 810, it has 8 cores (4x Cortex-A57 and 4x Cortex-A53) the four Cortex-A57 cores clocked at up to 2.0 GHz for high performance while gaming, and the other four cores are Cortex-A53 cores clocked at 1.5 GHz, which are power saving cores and they handle the background tasks and simple applications.
Clock Rate
The clock rate typically refers to the frequency at which a chip like a central processing unit (CPU), one core of a multi-core processor, is running and is used as an indicator of the processor's speed. It is measured in the SI unit hertz. The clock rate of the first generation of computers was measured in hertz or kilohertz, but in the 21st century the speed of modern CPUs is commonly advertised in gigahertz.
To identify which phone is faster if see how fast the processor. But it will not give you the inforamtion how fast your chip is. there are many factors that govern the cpu processing power. It depends of how work the CPU can perform in one cycle. How many instructions per clock it can execute. For example if a 2 ghz processor does 1 instruction per cycle and a 1ghz processor does 2 instruction per cycle, both the processors do exactly the same amount of work!
What is 45nm, 65nm ?
45nm & 65nm are sizes of the microscopic transistors that make up the CPU. Lesser the size of the transistor, more the number of transistors that can be fitted on the CPU board. More transistors can be fitted onto a chip, if their size is small. It means more implications can be made to the device.
Small transistors consume fewer watts and won’t get hot. It gives mobile device the ability to run at higher clock rate without draining-out the battery.
How performance affect phone usage
The performance of a processor is tested by performing different kinds of benchmarks on it.Benchmarking is usually associated with assessing performance characteristics of computer hardware, for example, the floating point operation performance of a CPU. Benchmarks are designed to mimic a particular type of workload on a component or system. Synthetic benchmarks do this by specially created programs that impose the workload on the component. Application benchmarks run real-world programs on the system. While application benchmarks usually give a much better measure of real-world performance on a given system, synthetic benchmarks are useful for testing individual components, like a hard disk or networking device.
Just by doing one benchmark will not give the exact real world performance. As you know mobile processors have multiple processors, some benchmarks will measure the top speed of a single core with more power redirected to it in the turbo mode, but that benchmark wont tell you how your phone will perform with heavier load spread across all the processing cores. Some benchmarks will tell you how much graphics performance of the phone is.
Here are the Xiaomi Mi 4i Benchmarks http://www.fonearena.com/blog/138705/xiaomi-mi-4i-benchmarks.html
This tells us how much potential our phones have. So the better the scores you get in the above benchmarks it will tell you what all your phone can do. Lower scores mean that your phone is laggy when playing games and also the Android UI gets laggy at times.
Overclocking
Overclocking is the process of forcing a computer or hardware component to operate faster than the manufacturer-specified clock frequency. Operating voltages may also be changed (increased) accordingly, which can also increase the speed at which operation remains stable. Most overclocking techniques increase power consumption, ending up with generating more heat that must be dispersed if the component is to remain operational.
So, is Android overclocking safe? Well, we can say yes, though you should overclock only 10-20% of your stock frequency, or else your device will encounter another issue: battery drain. Anyhow, let’s say you overclock your handset from 1 GHz to 1.5 GHz; now this doesn’t mean that your Android device will constantly run on 1.5 GHz, as that power will be used only when needed (running games, or multiple apps, showing HD movies or running 3D tools).
Overclocking will give a significant boost to your phone, and you can run that hd game smoothly that used to earlier lag. But do keep in mind that overclocking can do damage to your cpu and other components, and also it will void your warranty.
Comparison between processors
Snapdragon 810 MSM8994 vs the Mediatek Helio X20 They are currently the fastest mobile processors. so it would be interesting to compare them.
Lets have a look how they perform
Right off the bat, MediaTek manages to raise eyebrows with what is the first 10 core System-on-a-Chip design. The 10 processor cores are arranged in a tri-cluster orientation, which is a new facet against a myriad of dual-cluster big.LITTLE heterogeneous CPU designs. The three clusters consist of a low power quad-core A53 cluster clocked at 1.4 GHz, a power/performance balanced quad-core A53 cluster at 2.0GHz, and an extreme performance dual-core A72 cluster clocked in at 2.5GHz. To achieve this tri-cluster design, MediaTek chose to employ a custom interconnect IP called the MediaTek Coherent System Interconnect (MCSI).
The Qualcomm Snapdragon 810 MSM8994 has a highperforming CPU with a maximum clock speed of 2,500.00 MHz. It has 8 core(s), resulting in extremely efficient multi-tasking when compared to dual core processors. The Snapdragon 810 is also based on ARM's big.LITTLE concept, which combines different CPU cores for an optimal combination of performance and power consumption. In this case, there are four fast Cortex-A57 cores clocked at up to 2.0 GHz. Furthermore, the SoC integrates four slower, but much more efficient Cortex-A53 cores clocked at 1.5 GHz, which will handle background tasks and simple applications as i had said earlier.
All eight cores can be active at the same time, although most applications aren't parallelized to support 8 cores efficiently. Both Cortex-A53 and -A57 are based on the ARMv8 ISA and are therefore 64-bit capable.
On the GPU side, the X20 seemed to be the first officially announced Mali T800 series GPU SoC. MediaTek explains that this is a still-unreleased ARM Mali high-end GPU similar to the T880. MediaTek initially chose a more conservative MP4 configuration clocked in at 700MHz, although final specifications are being withheld at this time. It should be noted that Mediatek has traditionally never aimed very high in terms of GPU configurations. It could be considered that the GPU in the X20 could still remain competitive in prolonged sustained loads as we saw larger Mali implementations such as Samsung's Exynos SoCs not being able to remain in the thermal envelope at their maximum rated frequencies. Initial relative estimates of the X20, expressed by MediaTek, compared to the Helio X10's G6200 see a 40% improvement in performance with a 40% drop in power
The Adreno 430 outperforms the previous Adreno 420 (Snapdragon 805) by almost 30 percent. Therefore, the chip ends up slightly faster than the PowerVR GX6450 (Apple A8), but somewhat below the Mali-T760 MP8 (Exynos 7420). However, the GPU may throttle significantly in long-lasting benchmarks or games. Nevertheless, it offers sufficient power for high-end devices with display resolutions exceeding FullHD. Also on the video side: both SoCs boast dedicated HEVC/H.265 decode hardware. Only the Snapdragon 810 has a hardware HEVC encoder however. The 810 can support up to two 4Kx2K displays (1 x 60Hz + 1 x 30Hz), while the 808 supports a maximum primary display resolution of 2560 x 1600.
On the memory side, MediaTek remains with a 2x32bit LPDDR3 memory interface running at 933MHz. The 810 on the other hand features a 64-bit wide LPDDR4-1600 interface (3200MHz data rate, 25.6GB/s memory bandwidth).
| Qualcomm Snapdragon 810 | Mediatek Helio X20 |
| CPU | 4 x ARM Cortex A57 + 4 x ARM Cortex A53 (big.LITTLE) |
4x Cortex A53 @1.4GHz+
4x Cortex A53 @2.0GHz +
2x Cortex A72
|
| GPU | Adreno 430 |
Mali T8MP4
|
Integrated
Modem | 9x35 core, LTE Category 6/7, DC-HSPA+, DS-DA |
LTE Cat. 6
300Mbps DL 50Mbps UL
2x20MHz C.A.
(DL)
|
| Memory Controller | 2 x 32-bit @1600Mhz LPDDR4 |
2x 32-bit @933MHz
LPDDR3
|
you can also find comparisons between snapdragon processors herehttps://www.qualcomm.com/products/snapdragon/processors/comparison |
