On Sunday prior to [1]releasing Linux 6.15-rc1 , one of the last feature pulls was merging updates for the Turbostat utility that lives within the Linux kernel source tree. The Turbostat tool provides CPU frequency and power statistics along with the ability to query temperatures and other CPU metrics on AMD and Intel processors.

Aligned for the Linux 6.15 cycle with the handy Turbostat command-line utility is introducing CPUidle governor debug telemetry, various minor code fixes, and bumping the maximum CPU core limit to 8192 cores.

Turbostat had maintained a static limit of 1,024 CPU core maximum but that limit is now revised to 8,192 cores. Adjusting this limit is coming at the request of HPE that was hitting Turbostat failing due to trying the tool on an unspecified 1152 core/thread system. This 8,192 limit aligns with other CPU maximum core limits currently in place within the Linux kernel and elsewhere.

HPE didn't specify the 1152 core system hitting this Turbostat issue. 1152 may seem like an odd core/thread count but 1152 divided by 4 is 288. Intel does have the rare 288-core flagship Xeon 6900E E-Core "Sierra Forest" server processor, so it's possible it could be that in a 4P server configuration. Or who knows what other platforms HPE may be preparing on the horizon from either AMD or Intel.

In any event [2]here are the Turbostat patches that made it into Linux 6.15 ahead of the 6.15-rc1 release on Sudnay.



[1] https://www.phoronix.com/news/Linux-6.15-rc1-Released

[2] https://lore.kernel.org/linux-pm/20250406185820.765991-1-lenb@kernel.org/