[V3,0/2] cpufreq: cppc: Add support for frequency invariance

Message

Viresh Kumar Jan. 28, 2021, 10:48 a.m. UTC

Hello,

CPPC cpufreq driver is used for ARM servers and this patch series tries
to provide counter-based frequency invariance support for them in the
absence for architecture specific counters (like AMUs).

This is tested with some hacks, as I didn't have access to the right
hardware, on the ARM64 hikey board to check the overall functionality
and that works fine.

Vincent/Ionela, it would be nice if you guys can give this a shot on
some real hardware where counters work.

This is based of pm/linux-next (need some stuff from the arm64 tree).
These patches should get merged via the arm64 tree only for the same
reason.

Changes since V2:
- Not sending as an RFC anymore.
- Several renames, reordering of code in 1/2 based on Ionela's comments.
- Several rebase changes for 2/2.
- The freq_scale calculations are optimized a bit.
- Better overall commenting and commit logs.

Changes since V1:
- The interface for setting the callbacks is improved, so different
  parts looking to provide their callbacks don't need to think about
  each other.

- Moved to per-cpu storage for storing the callback related data, AMU
  counters have higher priority with this.

--
viresh

Viresh Kumar (2):
  topology: Allow multiple entities to provide sched_freq_tick()
    callback
  cpufreq: cppc: Add support for frequency invariance

 arch/arm64/include/asm/topology.h |  10 +-
 arch/arm64/kernel/topology.c      |  89 +++++++--------
 drivers/base/arch_topology.c      |  56 +++++++++-
 drivers/cpufreq/cppc_cpufreq.c    | 179 ++++++++++++++++++++++++++++--
 include/linux/arch_topology.h     |  15 ++-
 kernel/sched/core.c               |   1 +
 6 files changed, 274 insertions(+), 76 deletions(-)