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Intel releases patch for Alder Lake’s Thread Director Linux support to increase performance and energy efficiency

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Intel launched several patches for the Linux series of operating systems to aid in increasing Alder Lake's performance through the P and E cores, or Performance and Efficiency cores.

Linux OS to receive support for Intel's Alder Lake Golden Cove and Gracemont performance and efficiency cores through upcoming patches

With the release of Intel's 12th Gen Core Alder Lake series of CPUs, it was discovered that performance for the new CPUs was more efficient in Microsoft Windows 11 than in the Linux operating system. This is due to Linux not having adequate support for Intel's Thread Director technology that allows for the operating system to access high-performing Golden Cove cores and the energy-efficient Gracemont cores properly. Intel's Thread Director is created from the Enhanced Hardware Feedback Interface or HFI.

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Website Phoronix reports that the current firmware in Linux uses an algorithm to plan which of the Performance or Efficiency cores utilized by the ITMT/Turbo Boost Max 3.0 driver are accessed at the time. In turn, due to the nature of Linux choosing to lean more towards higher performance, such as what is found in Golden Cove's clock speed, while at the same time lessening the utilization of the energy-efficient Gracemont cores.

Enter the Intel Hardware Feedback Interface—a table created by the HFI to help provide information for both the performance and energy efficiency of the computer's processor. The HFI table, working together with the OS and the hardware, is constantly updated depending on any changes in the operating conditions or any actions from external factors at the time. An example of this process is the thermal limits reached by the operating system or changes made by the thermal design power.

Intel explains the new patch in further detail.

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In short, Intel's HFI calculates the power efficiency and performance capability of the processor, giving it a numerical value to the core (0 - 255), and communicates that information to the operating system. This real-time communication from the HFI allows for the hardware to adapt to the current capabilities of the system and communicate to the operating system to make recommendations on what to limit at the given time, such as minimizing any scheduled tasks that would affect the energy efficiency, performance levels, or temperature of the system.

Currently, the newest patch series is in the revision stages, and no word yet has been made whether the patches will be part of the upcoming Linux 5.17 update, or released at a further date sometime this year.

Sources: Phoronix, Tom's Hardware

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