Intel Turbo Boost Max 3.0 Testing On The Linux 4.11 Kernel

With the upcoming Linux 4.11 kernel release there is better support for Intel Turbo Boost Max 3.0 after originally it didn't look like this feature would be available for Linux. Under Linux 4.11, my Core i7 6800K + MSI X99A WORKSTATION box is now working with "ITMT" enabled, so here are some quick benchmarks.

With the earlier implementation of Turbo Boost Max 3.0 in Linux 4.10, TBM3 would only work for motherboards exposing hardware P-States. My X99A Workstation board didn't expose it, but with Linux 4.11 is support for non-HWP systems with TBM3-capable processors. Turbo Boost Max 3.0 on newer Broadwell-E CPUs is designed to boost single-threaded workloads and under Windows is advertised as potentially offering up to 15% better performance.

With the Core i7 6800K for testing it has a 3.4GHz base frequency, 3.6GHz turbo frequency, and 3.8GHz for its Turbo Boost Max 3.0 frequency. Or basically about a 5% higher maximum clock frequency for single-threaded workloads getting to take advantage of TBM3. The functionality can be toggled at runtime via /proc/sys/kernel/sched_itmt_enabled.



Though from this Core i7 6800K testing on Linux 4.11 Git, any benefit appears to be very minimal.


With CPUs like the Core i7 6950X it might be more apparent with having a 3.0GHz base frequency, 3.5GHz turbo frequency, and a TBM3.0 frequency of 4.0GHz -- a much bigger difference than this lone Broadwell-E CPU I have.



If anyone with TBM3-capable CPUs have experienced different results, feel free to share them in the forums or if you have encountered any interesting single-threaded Linux workloads benefiting well from Turbo Boost Max.