Arm’s Cortex A55

Arm’s 5-series cores are meant for tasks where performance barely matters, but power and area efficiency are top priorities. Because they’re less performance sensitive, 5-series cores tend to be superseded less often than their more sophisticated counterparts. Cortex A53 started out Arm’s 5-series lineup in 2012, and served across three generations of 7-series cores (A57, A72, and A73). Five years later, Arm refreshed the 5-series line with the Cortex A55. A55 then served as a little core partner to A75, A76, and A78.From Arm’s websiteHere, I’ll be looking at the A55 primarily in the Mediatek Genio 1200, using the Radxa NIO 12L single board computer. The Mediatek Genio 1200 has four A55 cores and four A78 cores in what Arm calls the DynamIQ Shared Unit (DSU). The DSU is a cluster with 2 MB of L3 cache, and can host different core types without creating cluster boundaries between them. The Genio 1200 runs its A55 cores at 2 GHz, and gives each A55 core 128 KB of L2 cache. For memory,…