Hello. On pondělí 18. září 2023 10:14:00 CEST Meng Li wrote: > Hi all: > > The core frequency is subjected to the process variation in semiconductors. > Not all cores are able to reach the maximum frequency respecting the > infrastructure limits. Consequently, AMD has redefined the concept of > maximum frequency of a part. This means that a fraction of cores can reach > maximum frequency. To find the best process scheduling policy for a given > scenario, OS needs to know the core ordering informed by the platform through > highest performance capability register of the CPPC interface. > > Earlier implementations of amd-pstate preferred core only support a static > core ranking and targeted performance. Now it has the ability to dynamically > change the preferred core based on the workload and platform conditions and > accounting for thermals and aging. > > Amd-pstate driver utilizes the functions and data structures provided by > the ITMT architecture to enable the scheduler to favor scheduling on cores > which can be get a higher frequency with lower voltage. > We call it amd-pstate preferred core. > > Here sched_set_itmt_core_prio() is called to set priorities and > sched_set_itmt_support() is called to enable ITMT feature. > Amd-pstate driver uses the highest performance value to indicate > the priority of CPU. The higher value has a higher priority. > > Amd-pstate driver will provide an initial core ordering at boot time. > It relies on the CPPC interface to communicate the core ranking to the > operating system and scheduler to make sure that OS is choosing the cores > with highest performance firstly for scheduling the process. When amd-pstate > driver receives a message with the highest performance change, it will > update the core ranking. > > Changes form V6->V7: > - x86: > - - Modify kconfig about X86_AMD_PSTATE. > - cpufreq: amd-pstate: > - - modify incorrect comments about scheduler_work(). > - - convert highest_perf data type. > - - modify preferred core init when cpu init and online. > - acpi: cppc: > - - modify link of CPPC highest performance. > - cpufreq: > - - modify link of CPPC highest performance changed. > > Changes form V5->V6: > - cpufreq: amd-pstate: > - - modify the wrong tag order. > - - modify warning about hw_prefcore sysfs attribute. > - - delete duplicate comments. > - - modify the variable name cppc_highest_perf to prefcore_ranking. > - - modify judgment conditions for setting highest_perf. > - - modify sysfs attribute for CPPC highest perf to pr_debug message. > - Documentation: amd-pstate: > - - modify warning: title underline too short. > > Changes form V4->V5: > - cpufreq: amd-pstate: > - - modify sysfs attribute for CPPC highest perf. > - - modify warning about comments > - - rebase linux-next > - cpufreq: > - - Moidfy warning about function declarations. > - Documentation: amd-pstate: > - - align with ``amd-pstat`` > > Changes form V3->V4: > - Documentation: amd-pstate: > - - Modify inappropriate descriptions. > > Changes form V2->V3: > - x86: > - - Modify kconfig and description. > - cpufreq: amd-pstate: > - - Add Co-developed-by tag in commit message. > - cpufreq: > - - Modify commit message. > - Documentation: amd-pstate: > - - Modify inappropriate descriptions. > > Changes form V1->V2: > - acpi: cppc: > - - Add reference link. > - cpufreq: > - - Moidfy link error. > - cpufreq: amd-pstate: > - - Init the priorities of all online CPUs > - - Use a single variable to represent the status of preferred core. > - Documentation: > - - Default enabled preferred core. > - Documentation: amd-pstate: > - - Modify inappropriate descriptions. > - - Default enabled preferred core. > - - Use a single variable to represent the status of preferred core. > > Meng Li (7): > x86: Drop CPU_SUP_INTEL from SCHED_MC_PRIO for the expansion. > acpi: cppc: Add get the highest performance cppc control > cpufreq: amd-pstate: Enable amd-pstate preferred core supporting. > cpufreq: Add a notification message that the highest perf has changed > cpufreq: amd-pstate: Update amd-pstate preferred core ranking > dynamically > Documentation: amd-pstate: introduce amd-pstate preferred core > Documentation: introduce amd-pstate preferrd core mode kernel command > line options > > .../admin-guide/kernel-parameters.txt | 5 + > Documentation/admin-guide/pm/amd-pstate.rst | 58 +++++- > arch/x86/Kconfig | 5 +- > drivers/acpi/cppc_acpi.c | 13 ++ > drivers/acpi/processor_driver.c | 6 + > drivers/cpufreq/amd-pstate.c | 197 ++++++++++++++++-- > drivers/cpufreq/cpufreq.c | 13 ++ > include/acpi/cppc_acpi.h | 5 + > include/linux/amd-pstate.h | 6 + > include/linux/cpufreq.h | 5 + > 10 files changed, 291 insertions(+), 22 deletions(-) When applied on top of v6.5.3 this breaks turbo on my 5950X after suspend/resume cycle. Please see the scenario description below. If I boot v6.5.3 + this patchset, then `turbostat` reports ~4.9 GHz on core 0 where `taskset -c 0 dd if=/dev/zero of=/dev/null` is being run. After I suspend the machine and then resume it, and run `dd` again, `turbostat` reports the core to be capped to a stock frequency of ~3.4 GHz. Rebooting the machine fixes this, and the CPU can boost again. If this patchset is reverted, then the CPU can turbo after suspend/resume cycle just fine. I'm using `amd_pstate=guided`. Is this behaviour expected? Thanks. -- Oleksandr Natalenko (post-factum)
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