linux/include
Viresh Kumar 4c38f2df71 cpufreq: CPPC: Add support for frequency invariance
The Frequency Invariance Engine (FIE) is providing a frequency scaling
correction factor that helps achieve more accurate load-tracking.

Normally, this scaling factor can be obtained directly with the help of
the cpufreq drivers as they know the exact frequency the hardware is
running at. But that isn't the case for CPPC cpufreq driver.

Another way of obtaining that is using the arch specific counter
support, which is already present in kernel, but that hardware is
optional for platforms.

This patch updates the CPPC driver to register itself with the topology
core to provide its own implementation (cppc_scale_freq_tick()) of
topology_scale_freq_tick() which gets called by the scheduler on every
tick. Note that the arch specific counters have higher priority than
CPPC counters, if available, though the CPPC driver doesn't need to have
any special handling for that.

On an invocation of cppc_scale_freq_tick(), we schedule an irq work
(since we reach here from hard-irq context), which then schedules a
normal work item and cppc_scale_freq_workfn() updates the per_cpu
arch_freq_scale variable based on the counter updates since the last
tick.

To allow platforms to disable this CPPC counter-based frequency
invariance support, this is all done under CONFIG_ACPI_CPPC_CPUFREQ_FIE,
which is enabled by default.

This also exports sched_setattr_nocheck() as the CPPC driver can be
built as a module.

Cc: linux-acpi@vger.kernel.org
Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com>
Tested-by: Ionela Voinescu <ionela.voinescu@arm.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
2021-03-22 08:55:28 +05:30
..
acpi IOMMU Updates for Linux v5.12 2021-02-22 10:31:29 -08:00
asm-generic RISC-V Patches for the 5.12 Merge Window 2021-02-26 10:28:35 -08:00
clocksource
crypto Keyrings miscellany 2021-02-23 16:09:23 -08:00
drm drm/drm_vblank: set the dma-fence timestamp during send_vblank_event 2021-02-24 21:05:54 +05:30
dt-bindings RISC-V Patches for the 5.12 Merge Window 2021-02-26 10:28:35 -08:00
keys
kunit
kvm
linux cpufreq: CPPC: Add support for frequency invariance 2021-03-22 08:55:28 +05:30
math-emu
media Fixes around VM_FPNMAP and follow_pfn 2021-02-22 17:45:02 -08:00
memory
misc
net net: icmp: pass zeroed opts from icmp{,v6}_ndo_send before sending 2021-02-23 11:29:52 -08:00
pcmcia
ras
rdma
scsi
soc RISC-V Patches for the 5.12 Merge Window 2021-02-26 10:28:35 -08:00
sound ALSA/ASoC/SOF/SoundWire: fix Kconfig issues 2021-03-02 18:30:07 +01:00
target scsi: target: core: Add cmd length set before cmd complete 2021-02-22 22:21:29 -05:00
trace block-5.12-2021-02-27 2021-02-28 11:23:38 -08:00
uapi * Doc fixes 2021-03-04 11:26:17 -08:00
vdso
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xen xen/events: add per-xenbus device event statistics and settings 2021-02-23 10:07:11 -06:00