[PATCH v4 0/5] Rework system pressure interface to the scheduler

Vincent Guittot
2024-01-09T16:47:00Z

Following the consolidation and cleanup of CPU capacity in [1], this serie
reworks how the scheduler gets the pressures on CPUs. We need to take into
account all pressures applied by cpufreq on the compute capacity of a CPU
for dozens of ms or more and not only cpufreq cooling device or HW
mitigiations. We split the pressure applied on CPU's capacity in 2 parts:
- one from cpufreq and freq_qos
- one from HW high freq mitigiation.

The next step will be to add a dedicated interface for long standing
capping of the CPU capacity (i.e. for seconds or more) like the
scaling_max_freq of cpufreq sysfs. The latter is already taken into
account by this serie but as a temporary pressure which is not always the
best choice when we know that it will happen for seconds or more.

[1] https://lore.kernel.org/lkml/20231211104855.558096-1-vincent.guittot@linaro.org/

Change since v3:
- Fix uninitialized variables in cpufreq_update_pressure()

Change since v2:
- Rework cpufreq_update_pressure()

Change since v1:
- Use struct cpufreq_policy as parameter of cpufreq_update_pressure()
- Fix typos and comments
- Make sched_thermal_decay_shift boot param as deprecated

Vincent Guittot (5):
cpufreq: Add a cpufreq pressure feedback for the scheduler
sched: Take cpufreq feedback into account
thermal/cpufreq: Remove arch_update_thermal_pressure()
sched: Rename arch_update_thermal_pressure into
arch_update_hw_pressure
sched/pelt: Remove shift of thermal clock

.../admin-guide/kernel-parameters.txt | 1 +
arch/arm/include/asm/topology.h | 6 +-
arch/arm64/include/asm/topology.h | 6 +-
drivers/base/arch_topology.c | 26 ++++----
drivers/cpufreq/cpufreq.c | 36 +++++++++++
drivers/cpufreq/qcom-cpufreq-hw.c | 4 +-
drivers/thermal/cpufreq_cooling.c | 3 -
include/linux/arch_topology.h | 8 +--
include/linux/cpufreq.h | 10 +++
include/linux/sched/topology.h | 8 +--
.../{thermal_pressure.h => hw_pressure.h} | 14 ++---
include/trace/events/sched.h | 2 +-
init/Kconfig | 12 ++--
kernel/sched/core.c | 8 +--
kernel/sched/fair.c | 63 +++++++++----------
kernel/sched/pelt.c | 18 +++---
kernel/sched/pelt.h | 16 ++---
kernel/sched/sched.h | 22 +------
18 files changed, 144 insertions(+), 119 deletions(-)
rename include/trace/events/{thermal_pressure.h => hw_pressure.h} (55%)

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2.34.1