Thermal Budgets on a System-on-Chip

On a mobile device, when the processor works, it generates heat. This can lead to problems such as thermal throttling, which occurs when a System-on-Chip (SoC) gets too hot and begins to reduce the clock speed of the CPU and GPU. If the chip remains too hot, it may begin disabling blocks of hardware entirely, such as CPU cores. Reducing clock speed and disabling CPU blocks will impact performance and lead to performance spikes or consistently lower application performance. Every processor operation generates an amount of heat which may reduce the workload and the amount of operations per second.

Typically, mobile devices use a SoC which means that each processor is on the same die. As a result, the heat generated from one processor is indistinguishable from another. If the die gets too hot, clock speeds may be reduced or the whole chip might go into idle in order to compensate. Vulkan reduces the likelihood of thermal throttling by reducing the amount of work required by the CPU compared to other APIs, meaning that the CPU may run cooler than expected. On modern devices, even the home screens of most operating systems will utilise the GPU. When applied to a SoC platform, running the CPU at a cooler temperature results in increased CPU performance, as the GPU can be made to work harder before similar levels of heat generation are reached and things need to be throttled.