Android support three processor (CPU):ARM, Intel and MIPS. ARM is undoubtedly the most widely used. Because of the popularity of Intel on desktops and servers are known, but relatively small influence on the mobile industry. MIPS in the 32 bit and 64 bit embedded in the field has a long history, gained a lot of success, but the current Android with the lowest rate in three patients. In short, ARM is now the winner and Intel is the strongest opponents of ARM.
Then the ARM processor and Intel processor in the end what is the difference? Why is ARM so popular? Your smart mobile phone or tablet computer is the processor what exactly is important?
The processor (CPU)
The central processor (CPU) is your smart device of the brain. Its task is by executing a series of instructions to drive your equipment, including display, touch screen, modem, make a lump of metal and plastic mixture into bright smart phones or tablet computers.
The mobile device is very complex, the processor requires millions of lines of instructions can perform these devices people want to do. The speed and power consumption of the processor is essential. Speed affects the user experience, power battery life. The perfect mobile devices must have good performance and low power consumption.
This is why the choice of what kind of processor is very important. A super power, slow to react to the processor will quickly drain your battery, and a sophisticated and efficient processor to you bring high performance and longer battery life.
Overall, the first difference between ARM and Intel processor is used, the former reduced instruction set (RISC), while the latter uses complex instruction set (CISC).
In popular terms, RISC is smaller, more close to the atomic operations, and complex instruction set larger, more complex. Atomic operation, refers to each instruction most work can be done by the processor in a single operation, such as the addition of two registers.
Complex instructions describe an intent, but the processor must perform 3 or 4 more simple instructions to achieve this purpose. For example, you can command a complex instruction set processor the sum of 2 numbers, and the results stored in the main memory. In order to complete the command processor first from address 1 made the first number (operation 1), and then from the address of another 2 (2), then the number of sum (3), etc..
All modern processors use a so-called micro instruction concept, this is an internal processor instruction set, used to describe the processor can do atomic operation.
Complex instruction set processor actually executes 3 microinstructions. Of reduced instruction set processors, the instruction with the microinstruction is very close, and complex instruction set processor instructions need to be converted into some more streamlined micro instructions (like in front of the complex instruction set processors add examples in that.
That is to say, RISC processor in the decoder (for the processor told exactly what to do stuff) is much more simple and simple means of high efficiency and low power consumption.
Another major difference between ARM and Intel processor ARM is never just a design of low power processor. Its purpose is to design a low power processor, this is their strength. Intel is strong in design of ultra high performance desktop and server processor, and is doing good.
Intel is a desktop server industry leader. In the past 20 years all my PC, notebook and server (except one) are used in the Intel processor. However into the mobile industry, Intel still use desktop and the same complex instruction set architecture, to the hard squeezed to mobile devices using smaller processors.
Intel i7 processor average fever rate is 45 watts. ARM based system on chip (including graphics processor) the maximum instantaneous peak heating rate is about 3 watts, about Intel i7 processor 1/15. Intel is now a giant, employs a lot of smart people.
The latest Atom series processor using temperature control design with ARM processor is similar, for the Intel manufacturing process must use the latest 22 nm. In general, the number of nano manufacturing process is small, the higher the efficiency of energy use. The manufacturing process of ARM processor with a lower temperature, has a similar effect. For example, Qualcomm Xiaolong 805 processor using 28 nanometer manufacturing process.
For the 64 bit computing, ARM and Intel also have some significant differences. You know, Intel has not developed a 64 bit version of the x86 instruction set. The 64 bit instruction set, called x86-64 (sometimes referred to as x64), is actually the AMD design and development.
Story is this: Intel wants to engage in 64 bit computing, it knows if their own 32-bit x86 architecture evolution from 64 bit architecture, the new framework efficiency will be very low, so it got a new 64 bit processor project called IA64. Produced Itanium series processor.
At the same time, AMD knew that he was not made compatible with IA64 processor, so it extends x86, with 64 bit and 64 bit register addressing. The final out of the architecture, called AMD64, a 64 bit x86 processor version of the standard.
The success of IA64 project is not considered, now basically abandoned. Intel by the AMD64. The current Intel mobile solutions are given, is using the 64 bit instruction set of AMD development (slightly different) 64 bit processors.
ARM's story is not the same: see the calculation of 64 mobile devices demand, ARM released the ARMv8 64 architecture in 2011, this is for the crystallization of the next generation of ARM instruction set architecture work after several years. In order to principle and instruction on the basis of the original set of 64 bit architecture to develop a concise, ARMv8 used two execution mode, AArch32 and AArch64.
As the name suggests, a 32 bit code, running a 64 bit code. ARM ingenious design, is the processor can seamlessly switch between the two modes in operation. This means that the decoder 64 bit instruction is a new design, do not take into account the 32 bit instruction, and the processor can still be backwards compatible.
ARM big.LITTLE architecture is a creation Intel unable to copy. In the big.LITTLE architecture, the processor can be of different types. The traditional dual core or quad core processor contains the same 2 or 4 Nuclear nuclear. There are two nuclear as like as two peas a dual core Atom processor, providing the same performance, have the same power.
ARM via big.LITTLE to mobile devices launched in heterogeneous computing. This means that the processor in the core can have different performance and power consumption. When the normal operation of the equipment, the use of low power nuclear, but when you run a complex game, using a high performance nuclear.
This is what to do? The design of the processor, to consider the design of a lot of technology or not, these technical design determines processor performance and power consumption.
In one instruction is decoded and ready to perform, Intel and ARM processors. That is to say the decoding process is parallel.
The first step from memory read instruction, second step inspection and instruction decoding, third step instruction execution cycle. The advantage of the current instruction pipeline, when in the second step, the next instruction is the first step. When the instruction is executed in the third step, the next instruction is in the second step, and the next instruction in the first step, so the cycle.
In order to execute instructions, these lines can be designed to allow instructions are not in accordance with the order of the program is executed (out of order). Some smart logic structure can determine whether the next instruction depends on the current instruction execution results. Intel and ARM are out of order execution logic structure, as can be imagined, this structure is very complex. Complex means more power.
The Intel processor by designers opt out of order logic structure. This is not convenient for heterogeneous computing problems. The order of execution by ARM Cortex-A53, so some low power consumption. ARM and Cortex-A57 use out of order execution, so the faster but more power. The big.LITTLE processor can have both Cortex-A53 and Cortex-A57 kernel, how to use the kernel according to the specific needs of decision. When the background synchronization messages, do not need to order high speed implementation, need only when playing the game complex. Use the appropriate nuclear at the right time.
In principle, processor complex logical structure function is more higher, less efficiency is high, the instruction pipeline just one, including floating-point unit, single instruction multiple logical data (SIMD) (such as arm neon and Intel SSE/MMX), and a second level cache second level cache.
Each Atom system on chip, Intel only provides a solution of ARM and chip partners to provide chips and a variety of programs can be configured.
ARM is currently the mobile processor. ARM partners ARM based design to shipments of mobile and embedded market has reached 50 billion. For Android, ARM has become the standard, this is a problem for Intel and MIPS.
In order to solve this problem, Intel and MIPS to use special software to convert ARM instructions into their processor instructions. This is of course will reduce performance.
At present, MIPS and Intel claimed that about 90% of the Play Store compatible application. For the 150 of the most popular application, compatible with the rate of 100%. On the one hand, compatible with high rate indicates that the dominant position of ARM on the other hand, the other processor designers need to provide a compatibility layer.
The processor is a complex business. ARM, Intel and MIPS in unremitting efforts to provide the best technology to mobile devices, and obviously ARM is the boss. Have a low power, 64 bit design, concise and standard for heterogeneous computing, mobile computing, it seems that ARM will maintain their position at the top of the.