Hi All, This series adds support for obtaining an average CPU frequency based on a hardware provided feedback. The average frequency is being exposed via dedicated yet optional cpufreq sysfs attribute - cpuinfo_avg_freq. The architecture specific bits are being provided for AArch64, caching on existing implementation for FIE and AMUv1 support: the frequency scale factor, updated on each sched tick, serving as a base for retrieving the frequency for a given CPU, representing an average frequency reported between the ticks. The changes have been rather lightly (due to some limitations) tested on an FVP model. Note that, this series depends on [6] and [7] ! Relevant discussions: [1] https://lore.kernel.org/all/20240229162520.970986-1-vanshikonda@xxxxxxxxxxxxxxxxxxxxxx/ [2] https://lore.kernel.org/all/7eozim2xnepacnnkzxlbx34hib4otycnbn4dqymfziqou5lw5u@5xzpv3t7sxo3/ [3] https://lore.kernel.org/all/20231212072617.14756-1-lihuisong@xxxxxxxxxx/ [4] https://lore.kernel.org/lkml/ZIHpd6unkOtYVEqP@xxxxxxxxxxxxxxxxxxxxxxxxx/T/#m4e74cb5a0aaa353c60fedc6cfb95ab7a6e381e3c [5] https://lore.kernel.org/all/20240603081331.3829278-1-beata.michalska@xxxxxxx/ [6] https://lore.kernel.org/all/20240827154818.1195849-1-ionela.voinescu@xxxxxxx/ [7] https://lore.kernel.org/all/20250131155842.3839098-1-beata.michalska@xxxxxxx/ v10: - Assume '0' is still somewhat a valid frequency value (as per discussion) and that gets applied for show_cpuinfo for x86 - Excluded patch: "arm64: amu: Delay allocating cpumask for AMU FIE support" which has been sent out as a separate change at [7] - Added info on EAGAIN error within the docs - Switched to while loop instead of goto statement for arch_freq_get_on_cpu implementation v9: - Moved changes to arch_freq_get_on_cpu to a separate patch v8: - Drop introducing new function and reuse arch_freq_get_on_cpu, guarding its use in scaling_cur_freq sysfs handler with dedicated config for x86 v7: - Dropping 'arch_topology: init capacity_freq_ref to 0' patch from the series as this one has been sent separately as an independent change [https://lore.kernel.org/all/20240827154818.1195849-1-ionela.voinescu@xxxxxxx/] - Including in the series change that introduces new sysfs entry [PATCH 1/4] - Consequently modifying previously arch_freq_get_on_cpu to match reqs for new sysfs attribute - Dropping an idea of considering a CPU that has been idle for a while as a valid source of information for obtaining an AMU-counter based frequency - Some minor cosmetic changes v6: - delay allocating cpumask for AMU FIE support instead of invalidating the mask upon failure to register cpufreq policy notifications - drop the change to cpufreq core (for cpuinfo_cur_freq) as this one will be sent as a separate change v5: - Fix invalid access to cpumask - Reworked finding reference cpu when getting the freq v4: - dropping seqcount - fixing identifying active cpu within given policy - skipping full dynticks cpus when retrieving the freq - bringing back plugging in arch_freq_get_on_cpu into cpuinfo_cur_freq v3: - dropping changes to cpufreq_verify_current_freq - pulling in changes from Ionela initializing capacity_freq_ref to 0 (thanks for that!) and applying suggestions made by her during last review: - switching to arch_scale_freq_capacity and arch_scale_freq_ref when reversing freq scale factor computation - swapping shift with multiplication - adding time limit for considering last scale update as valid - updating frequency scale factor upon entering idle v2: - Splitting the patches - Adding comment for full dyntick mode - Plugging arch_freq_get_on_cpu into cpufreq_verify_current_freq instead of in show_cpuinfo_cur_freq to allow the framework to stay more in sync with potential freq changes CC: Jonathan Corbet <corbet@xxxxxxx> CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CC: Ingo Molnar <mingo@xxxxxxxxxx> CC: Borislav Petkov <bp@xxxxxxxxx> CC: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> CC: H. Peter Anvin <hpa@xxxxxxxxx> CC: Phil Auld <pauld@xxxxxxxxxx> CC: x86@xxxxxxxxxx CC: linux-doc@xxxxxxxxxxxxxxx Beata Michalska (4): cpufreq: Allow arch_freq_get_on_cpu to return an error cpufreq: Introduce an optional cpuinfo_avg_freq sysfs entry arm64: Provide an AMU-based version of arch_freq_get_on_cpu arm64: Update AMU-based freq scale factor on entering idle Documentation/admin-guide/pm/cpufreq.rst | 17 ++- arch/arm64/kernel/topology.c | 125 +++++++++++++++++++++-- arch/x86/kernel/cpu/aperfmperf.c | 2 +- arch/x86/kernel/cpu/proc.c | 7 +- drivers/cpufreq/Kconfig.x86 | 12 +++ drivers/cpufreq/cpufreq.c | 38 ++++++- include/linux/cpufreq.h | 2 +- 7 files changed, 183 insertions(+), 20 deletions(-) -- 2.25.1
