Re: [RFC V2 0/2] cpufreq: cppc: Add support for frequency invariance

From: Ionela Voinescu
Date: Wed Dec 16 2020 - 14:50:52 EST


Hi,

On Tuesday 15 Dec 2020 at 16:46:34 (+0530), Viresh Kumar wrote:
> Hello,
>
> CPPC cpufreq driver is used for ARM servers and this patch series tries
> to provide frequency invariance support for them.
>

Nitpick: cppc_cpufreq already supports cpufreq-based frequency
invariance, but not counter-based frequency invariance, when lacking
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.
>
> Ionela/Peter Puhov, it would be nice if you guys can give this a shot.
>

I'll be on holiday starting tomorrow until January. I fully intend to
review and test this but I'll have to set myself a deadline for January
to do it.

Sorry for the delay,
Ionela.

> This is based of pm/linux-next and patches [1] and [2] which I sent
> recently to cleanup arm64 topology stuff.
>
> 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
>
> [1] https://lore.kernel.org/lkml/7a171f710cdc0f808a2bfbd7db839c0d265527e7.1607579234.git.viresh.kumar@xxxxxxxxxx/
> [2] https://lore.kernel.org/lkml/5ffc7b9ed03c6301ac2f710f609282959491b526.1608010334.git.viresh.kumar@xxxxxxxxxx/
>
> 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 | 8 +-
> arch/arm64/kernel/topology.c | 89 +++++++++----------
> drivers/base/arch_topology.c | 56 +++++++++++-
> drivers/cpufreq/cppc_cpufreq.c | 140 +++++++++++++++++++++++++++++-
> include/linux/arch_topology.h | 14 ++-
> kernel/sched/core.c | 1 +
> 6 files changed, 244 insertions(+), 64 deletions(-)
>
> --
> 2.25.0.rc1.19.g042ed3e048af
>