Jorge Ramirez-Ortiz jorge.ramirez-ortiz@linaro.org writes:
This commit sets the power of the average CPU in SMP systems to SCHED_CAPACITY_SCALE.
Ignoring the condition "min_capacity==max_capacity" causes the function update_cpu_power( .. ) to generate out of range values. This is because the default value of middle_capacity is used in the final calculation instead of a valid scaling factor.
Incidentally, when out of range values are generated and if SCHED_FEAT(ARCH_POWER) is true, the load balancing algorithm makes incorrect scheduling decisions typically overallocating all the work on one of the CPU cores.
This proposed solution to arm64 is in line with the upstream solution present in arm32 since the commit below was merged:
- SHA: 816a8de0017f16c32e747abc5367bf379515b20a
- From: Sudeep KarkadaNagesha sudeep.karkadanagesha@arm.com
- Date: Mon, 17 Jun 2013 14:20:00 +0100
- Subject: ARM: topology: remove hwid/MPIDR dependency from cpu_capac
Signed-off-by: Jorge Ramirez-Ortiz jorge.ramirez-ortiz@linaro.org
With ack from Vincent, applied to LSK v3.10 topic branch v3.10/topic/arm64-hmp and merged into linux-linaro-lsk-v3.10
Thanks,
Kevin