Qcom elite uses per-cluster DVFS, with cores in a cluster share the same freq

2 points

2 years ago

I recently purchased a Xiaomi 15 Pro, which features two clusters (6 E-Cores + 2 P-Cores) with all cores in the same cluster operating at the same frequency.

In contrast, Apple has supported per-CPU DVFS since the M1, allowing each core to run at different frequencies and providing greater flexibility. BTW, Linux also supports this: https://lore.kernel.org/lkml/[email protected]/

> This driver implements CPU frequency scaling for Apple Silicon SoCs, including M1 (t8103), M1 Max/Pro/Ultra (t600x), and M2 (t8112).

> Each CPU cluster has its own register set, and frequency management is fully automated by the hardware; the driver only has to write one register. There is boost frequency support, but the hardware will only allow their use if only a subset of cores in a cluster are in non-deep-idle. Since we don't support deep idle yet, these frequencies are not achievable, but the driver supports them. They will remain disabled in the device tree until deep idle is implemented, to avoid confusing users.

Question: What’s the trade-off: PPA, R&D costs, or something else?