What is IPC and Why it Matters to Mobile 

In a previous blog about the Arm Cortex-X925 CPU, we discussed the significance of IPC (Instructions per Cycle) as a critical metric for evaluating CPU performance. Rather than focusing mostly on frequency as a performance metric, IPC measures the number of instructions a CPU can execute per clock cycle. As a result, IPC is a crucial metric for mobile where battery life and thermal management are key factors for real-world applications, user experiences and complex workloads on devices. 

Higher frequency not always best

A higher IPC score will indicate that more instructions are executed in one cycle, leading to better performance, even if the clock speed is lower. This is especially significant with memory bound workloads, where performance is gated by external factors to the CPU.  A higher IPC score also allows for a lower frequency for the CPU, which results in less drain on the battery and less power consumption leading to cooler devices. This is far more beneficial to mobile devices that rely on sustained performance. 

While a high frequency CPU can initially sound good, it does not depict the full picture about performance. Frequency indicates how fast CPU cycles are, but IPC indicates how much work is done across each of these cycles. In fact, meeting the highest frequency is only ever going to be used very rarely. For example, for gaming and other highly compute-intensive workloads, the CPUs will not be used at their maximum frequency, with the majority of the time spent running at a mid-range frequency where it is more efficient, leading to power savings on battery life and a cooler device – both of which are important metrics for improving the overall user experience.  

A CPU with higher IPC will be more performant for real-world applications and complex workloads, but in the same time duration. Even today’s AI-based applications, like chatbots, real-time language translation and virtual assistants, that have complex compute requirements will perform better if the CPU has got a higher IPC. Moreover, in terms of power-efficiency, having more instructions executed in one cycle, means that tasks can be completed quicker. This allows the CPU to spend less time in high power states and saves battery power. 

Architectural excellence

A central architectural feature for improved IPC in Armv9 CPU designs is SVE2 (Scalable Vector Extension 2), which incorporates new specialized vector instructions that are ideal for accelerating key workloads and applications for smartphones.  

SVE2 accelerates HDR video decode by around 10 percent, allowing users to experience longer battery life while streaming on-demand video for leading applications. Also, by accelerating commonly used image manipulation libraries, SVE2 enhances the smoothness of the user experience during video calls, while improving visual quality. This includes a better experience on camera rotating, switching, and applying image filters.​ 

Furthermore, SVE2 is “vector length agnostic”, which means code development will work on larger vector lengths, like 256b for example. This ensures forward compatibility with the ongoing evolution of mobile computing, which includes forthcoming process nodes that will favor logic scaling as opposed to RAMs. This means that the mobile market can accommodate larger vector lengths that benefit SVE code present in games and AI models. 

Looking deeper at the design, a higher IPC performance can be achieved through a range of specific microarchitectural improvements. These include, but are not limited to: 

• Superscalar, out-of-order execution 

• Branch Prediction and prefetchers 

• Data speculation 

• Adequate Cache choices 

Arm Cortex CPUs have a long history of incorporating various similar microarchitectural improvements year-on-year to achieve record levels of performance. 

The latest range of Armv9 CPUs for mobile

The architecture features and microarchitectural improvements outlined above are at the heart of our latest Armv9 CPUs for the mobile market. Cortex-X925, which is at the core of MediaTek’s Dimensity 9400 for flagship smartphones like the vivo X200 Series, is designed to include an upgrade to the private L2 cache, increasing it from 2MB to 3MB. This improvement significantly uplifts overall CPU performance and power efficiency, especially when coupled with Cortex-X925’s ability to prefetch data and complex instructions more quickly and efficiently. Thanks to this, the Arm compute platform delivered amazing double digit IPC performance improvements in 2024. 

As a result, there are a range of real-world performance improvements for the end-user, including faster application responses, better gaming experiences, smoother video streaming, faster web browsing and seamless multi-tasking. At the same time, all these real-world experiences can be enjoyed for longer because of the power-efficiency improvements from a higher IPC. 

Meanwhile, the Arm Cortex-A725 CPU, which is considered to be the “workhorse” for CPU workloads, provides a series of targeted updates focused on key AI and gaming use cases where superior sustained performance is needed. This helps to deliver a 35 percent improvement in performance efficiency and 25 percent improvement in power efficiency compared to the Arm Cortex-A720 CPU. 

In the Armv9.2 cluster, each CPU component covers the broad range of real-world use cases and complex workloads. For example, Cortex-X925 handles the “bursty” workloads of launching applications and web-browsing and Cortex-A725 provides the sustained performance for improved days of use (the average time users can spend on certain use cases on their devices before the battery dies) across the most popular mobile use cases, including gaming, web browsing, camera-based applications and video streaming. 

Arm at MWC 2025

At Mobile World Congress (MWC) 2025, Arm will be demonstrating a variety of real-world use cases running on Arm-powered smartphones, including the vivo X200 Series. From generative AI on the device, including chatbots, virtual assistants, and audio generation, to AAA gaming on mobile, the demos show how a higher IPC contributes to a better, smoother overall user experience. 

Enabling the best possible mobile experience

Fundamentally, mobile devices require a mix of performance and power-efficiency, which is exactly what IPC delivers. This means users can experience their favorite applications that require high compute performance over a longer period of time. The latest Armv9 CPUs combine leading IPC with high clock frequency for high levels of performance and efficiency, providing the best possible user experience to the end-user. This is part of the reason why 99 percent of the world’s smartphones are built on the Arm compute platform.