Unable to Reach Peak Boost Frequency (3.63GHz) on Dimensity 9400 Prime Core (CPU7)

General Discussion
1

Hi MediaTek Community,

I am performing pointer-chasing / memory latency microbenchmarking on a Vivo X200 Pro (Dimensity 9400).

According to the SoC specifications and scaling_available_frequencies, the Prime Core (Cortex-X925 / CPU7) should support frequencies up to ~3.626GHz.

Issue:
Despite applying sustained computational load, CPU7 consistently plateaus around 2.3GHz and never transitions to the higher OPP (Operating Performance Point) states.

What I have tried:

  1. CPU affinity:

    • Used sched_setaffinity() to pin workload to CPU7.

  2. Code-based warmup:

    • Added a 2-second busy-loop using floating-point math (sin/tan) before measurement to trigger DVFS ramp-up.

  3. Cluster sideloading:

    • Ran concurrent worker threads on sibling cores (CPU4-CPU6) to wake the cluster/power domain.

  4. Manual cpufreq override:

    • Attempted to write:
      /sys/devices/system/cpu/cpu7/cpufreq/scaling_min_freq

    • Permission denied on non-root production device.

Observations:

  • scaling_available_frequencies includes ~3.62GHz entries.

  • scaling_cur_freq never exceeds ~2,300,000 kHz during testing.

  • Device temperature remains below ~30°C.

  • Performance / Monster mode enabled.

  • Device connected to charger.

Questions:

  1. Is there a MediaTek PerfService API or vendor-specific performance hint required to enter turbo OPP states on Dimensity 9400?

  2. Does the DVFS governor require a specific workload pattern or instruction mix (e.g. NEON/vector/FMA instructions) before boosting beyond 2.3GHz?

  3. Are there firmware-level thermal or power constraints that prevent CPU7 from reaching peak frequency during single-core microbenchmark workloads on retail devices?

Any guidance on reliably triggering peak single-core frequency for benchmarking would be greatly appreciated.

3

Hi @Abhishek_Vishwakarma ,

The Dimensity 9400 is not part of the Genio platform.

Please contact Vivo customer support for assistance.

Thanks.