cd0ed03a89
The Frequency Invariance Engine (FIE) is providing a frequency scaling correction factor that helps achieve more accurate load-tracking. So far, for arm and arm64 platforms, this scale factor has been obtained based on the ratio between the current frequency and the maximum supported frequency recorded by the cpufreq policy. The setting of this scale factor is triggered from cpufreq drivers by calling arch_set_freq_scale. The current frequency used in computation is the frequency requested by a governor, but it may not be the frequency that was implemented by the platform. This correction factor can also be obtained using a core counter and a constant counter to get information on the performance (frequency based only) obtained in a period of time. This will more accurately reflect the actual current frequency of the CPU, compared with the alternative implementation that reflects the request of a performance level from the OS. Therefore, implement arch_scale_freq_tick to use activity monitors, if present, for the computation of the frequency scale factor. The use of AMU counters depends on: - CONFIG_ARM64_AMU_EXTN - depents on the AMU extension being present - CONFIG_CPU_FREQ - the current frequency obtained using counter information is divided by the maximum frequency obtained from the cpufreq policy. While it is possible to have a combination of CPUs in the system with and without support for activity monitors, the use of counters for frequency invariance is only enabled for a CPU if all related CPUs (CPUs in the same frequency domain) support and have enabled the core and constant activity monitor counters. In this way, there is a clear separation between the policies for which arch_set_freq_scale (cpufreq based FIE) is used, and the policies for which arch_scale_freq_tick (counter based FIE) is used to set the frequency scale factor. For this purpose, a late_initcall_sync is registered to trigger validation work for policies that will enable or disable the use of AMU counters for frequency invariance. If CONFIG_CPU_FREQ is not defined, the use of counters is enabled on all CPUs only if all possible CPUs correctly support the necessary counters. Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com> Reviewed-by: Lukasz Luba <lukasz.luba@arm.com> Acked-by: Sudeep Holla <sudeep.holla@arm.com> Cc: Sudeep Holla <sudeep.holla@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
40 lines
1.0 KiB
C
40 lines
1.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_TOPOLOGY_H
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#define __ASM_TOPOLOGY_H
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#include <linux/cpumask.h>
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#ifdef CONFIG_NUMA
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struct pci_bus;
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int pcibus_to_node(struct pci_bus *bus);
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#define cpumask_of_pcibus(bus) (pcibus_to_node(bus) == -1 ? \
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cpu_all_mask : \
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cpumask_of_node(pcibus_to_node(bus)))
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#endif /* CONFIG_NUMA */
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#include <linux/arch_topology.h>
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#ifdef CONFIG_ARM64_AMU_EXTN
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/*
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* Replace task scheduler's default counter-based
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* frequency-invariance scale factor setting.
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*/
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void topology_scale_freq_tick(void);
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#define arch_scale_freq_tick topology_scale_freq_tick
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#endif /* CONFIG_ARM64_AMU_EXTN */
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/* Replace task scheduler's default frequency-invariant accounting */
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#define arch_scale_freq_capacity topology_get_freq_scale
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/* Replace task scheduler's default cpu-invariant accounting */
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#define arch_scale_cpu_capacity topology_get_cpu_scale
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/* Enable topology flag updates */
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#define arch_update_cpu_topology topology_update_cpu_topology
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#include <asm-generic/topology.h>
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#endif /* _ASM_ARM_TOPOLOGY_H */
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