ARM processors are widely used in mobile devices and embedded systems. They offer a good balance of performance, power efficiency, and cost. However, ARM processors also have some limitations compared to x86 processors used in PCs and servers.
Key Advantages of ARM Processors
Power Efficiency
One of the biggest advantages of ARM processors is their power efficiency. ARM CPUs are designed to provide good performance at very low power draw. This makes them ideal for use in mobile devices like smartphones and tablets where battery life is critical. The power efficient design allows ARM chips to work without active cooling in many cases.
ARM implements advanced power saving features like clock gating, power gating, and dynamic voltage/frequency scaling. Most ARM CPUs are built on smaller and more power efficient manufacturing processes compared to x86 chips. The combination of architectural and manufacturing optimizations results in industry-leading power efficiency.
Cost
ARM processors tend to be cheaper than comparable x86 processors. One reason is that ARM licensing model spreads costs between many licensees while x86 chips are only made by Intel and AMD.
Also, R&D investments required for cutting-edge x86 performance often do not benefit the low-power ARM space. ARM chips are designed to be lean and efficient rather than maximizing performance at any cost.
The lower cost makes ARM ideal for price sensitive applications like embedded systems, home electronics, IoT devices etc. ARM’s cost structure enables new and innovative products that might not be viable with pricier CPUs.
Customization and Licensing Model
ARM Holdings designs the ARM instruction set architecture and CPU cores which it licenses to many semiconductor companies. Licensees like Qualcomm, Apple, Samsung, Huawei, Nvidia etc are free to customize ARM cores to optimize them for their target applications.
This licensing model allows ARM architecture to be tailored for the unique needs of different use cases. In contrast, x86 chips are controlled solely by Intel and AMD.
The flexibility of the ARM ecosystem results in greater innovation as licensees compete on implementation. It also lets ARM cores scale from tiny microcontrollers to high end mobile SoCs.
Embedded and IoT Friendly
The combination of smaller size, lower cost and power efficiency makes ARM a very attractive choice for embedded systems and IoT applications. ARM processors power most microcontrollers and SoCs designed for that space.
ARM offers embedded friendly features like memory protection, rich debug capabilities and support for real time operating systems. There is also a large pool of software developers skilled in programming ARM chips used in embedded devices.
Key Disadvantages of ARM Processors
Performance Limitations
While ARM CPUs are efficient, they lag behind x86 chips in terms of raw performance. For example, the latest ARM-based Apple M1 chip has impressive performance for a mobile SoC but still falls short of Intel and AMD’s flagship desktop and laptop processors.
There are a few key reasons for ARM’s lower performance:
- In-order execution limits instruction level parallelism
- Smaller cache sizes due to die area and cost constraints
- Typically fewer cores and threads than competing x86 parts
- Lower clock speeds to maintain power efficiency
While lagging in single thread performance, ARM chips are improving multi-threaded performance with added cores. But overall, applications requiring maximum CPU performance are still better served by x86 processors.
Software and Hardware Ecosystem Limitations
The ARM ecosystem has traditionally targeted mobile and embedded use cases. Consequently, its hardware and software support for desktop class applications is not as mature as x86 platforms.
Very few consumer operating systems are available for ARM. Windows provides a version for ARM but application compatibility remains spotty. Linux is the most popular OS on ARM but does not support many common desktop apps.
Driver support for ARM SoCs also tends to lag behind x86 versions, sometimes indefinitely if the ARM chip is niche. This complicates using ARM boards as general purpose computers.
Likewise, many productivity and creative applications like Adobe Creative Suite are only available for x86. The ARM app ecosystem outside mobile is quite limited currently.
Fragmentation Challenges
There is much greater diversity in the ARM ecosystem compared to just Intel and AMD for x86. While customization is a strength, it also causes fragmentation challenges.
OS and software vendors have to test across many different ARM chips that vary in performance, features and bugs. Qualcomm, Samsung and Apple ARM implementations can differ greatly, causing portability issues.
There is also fragmentation within the ARM instruction set architecture itself. Different licensees support a varying subset of the overall ARM ISA. This complicates software development as conditional code paths may be needed for each vendor’s ARM variant.
Conclusion
ARM processors offer excellent power efficiency making them ideal for mobile and embedded devices. However, they trade off peak performance and legacy software support compared to x86 desktop processors. ARM will likely close this gap over time as its cores scale up and ecosystem matures. But currently ARM CPUs are best suited for use cases that benefit from modest power efficient performance.
