Remove the rq::cpu_capacity_orig field and use arch_scale_cpu_capacity()
instead.
The scheduler uses 3 methods to get access to a CPU's max compute capacity:
- arch_scale_cpu_capacity(cpu) which is the default way to get a CPU's capacity.
- cpu_capacity_orig field which is periodically updated with
arch_scale_cpu_capacity().
- capacity_orig_of(cpu) which encapsulates rq->cpu_capacity_orig.
There is no real need to save the value returned by arch_scale_cpu_capacity()
in struct rq. arch_scale_cpu_capacity() returns:
- either a per_cpu variable.
- or a const value for systems which have only one capacity.
Remove rq::cpu_capacity_orig and use arch_scale_cpu_capacity() everywhere.
No functional changes.
Some performance tests on Arm64:
- small SMP device (hikey): no noticeable changes
- HMP device (RB5): hackbench shows minor improvement (1-2%)
- large smp (thx2): hackbench and tbench shows minor improvement (1%)
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20231009103621.374412-2-vincent.guittot@linaro.org
This commit 7d2078310c ("dt-bindings: arm: move cpu-capacity to a
shared loation") updates some references about capacity-dmips-mhz
property in this document.
The list of architectures using capacity-dmips-mhz omits RISC-V, so
supplements it here.
Signed-off-by: Song Shuai <suagrfillet@gmail.com>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com> # English
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Alex Shi <alexs@kernel.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230227105941.2749193-1-suagrfillet@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
RISC-V uses the same generic topology code as arm64 & while there
currently exists no binding for cpu-capacity on RISC-V, the code paths
can be hit if the property is present.
Move the documentation of cpu-capacity to a shared location, ahead of
defining a binding for capacity-dmips-mhz on RISC-V. Update some
references to this document in the process.
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Link: https://lore.kernel.org/r/20230104180513.1379453-2-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Add some documentation detailing the concepts, requirements and
implementation of capacity aware scheduling across the different scheduler
classes.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200731192016.7484-3-valentin.schneider@arm.com
Vincent Guittot
Song Shuai
Conor Dooley
Beata Michalska
Mauro Carvalho Chehab
Valentin Schneider