AMD P-State EPP Linux driver will allow users better performance and control power consumption with Ryzen & EPYC CPUs
A portion of the message from Perry Yuan, one of the AMD open-source engineers working on the P-State EPP driver, is shown below. Further, into the documentation, the team listed the change of events from the last version to the fourth version of the P-State EPP driver. This patchset implements one new AMD CPU frequency driver"amd-pstate-epp” instance for better performance and power control.CPPC has a parameter called energy preference performance (EPP).The EPP is used in the CCLK DPM controller to drive the frequency that a coreis going to operate during short periods of activity.EPP values will be utilized for different OS profiles (balanced, performance, power savings). AMD Energy Performance Preference (EPP) provides a hint to the hardwareif software wants to bias toward performance (0x0) or energy efficiency (0xff)The lowlevel power firmware will calculate the runtime frequency according to the EPP preference value. So the EPP hint will impact the CPU cores frequency responsiveness. We use the RAPL interface with “perf” tool to get the energy data of the package power. — Perry Yuan, AMD developer Changes from v3:
add one more document update patch for the active and passive modeintroduction. drive most of the feedback from Mario drive feedback from Rafael for the cppc_acpi driver. remove the epp raw data set/get function set the amd-pstate drive by passing the kernel parameter set amd-pstate driver disabled by default if no kernel parameterinput from booting get cppc_set_auto_epp and cppc_set_epp_perf combined pick up reviewed by a flag from Mario
AMD’s P-State EPP driver was to offer an alternative to the Advanced Configuration and Power Interface (ACPI) CPUFreq driver. The ACPI CPUFreq driver controls the frequency of a specified processor through ACPI, enabling communication between the hardware and the kernel. ACPI’s specification is an industry standard for better power consumption management in PCs and laptops. ACPI defines the system’s common I/O, peripherals, and operating system compared to power consumption. You can check out more information about the new AMD P-State EPP driver on the kernel page. News Sources: Phoronix, Linux kernel
