/proc/sys/kernel/sched_domain/, isolcpus, CONFIG_CPUMASK_OFFSTACK
From: Rantala, Tommi T. (Nokia - FI/Espoo)
Date: Fri Feb 15 2019 - 14:29:21 EST
Hello,
/proc/sys/kernel/sched_domain/ seems to be somewhat broken when kernel
is configured without CONFIG_CPUMASK_OFFSTACK and booting with
isolcpus= option.
Example with 8x CPU.
With CONFIG_CPUMASK_OFFSTACK=y and "isolcpus=2":
# uname -r
5.0.0-0.rc3.git0.1.fc30.x86_64
# ls /proc/sys/kernel/sched_domain/*
/proc/sys/kernel/sched_domain/cpu0:
domain0
/proc/sys/kernel/sched_domain/cpu1:
domain0
/proc/sys/kernel/sched_domain/cpu2:
/proc/sys/kernel/sched_domain/cpu3:
domain0
/proc/sys/kernel/sched_domain/cpu4:
domain0
/proc/sys/kernel/sched_domain/cpu5:
domain0
/proc/sys/kernel/sched_domain/cpu6:
domain0
/proc/sys/kernel/sched_domain/cpu7:
domain0
Another kernel without CONFIG_CPUMASK_OFFSTACK and "isolcpus=2", so
directories missing for CPUs 2-7:
# ls /proc/sys/kernel/sched_domain/
cpu0 cpu1
# ls /proc/sys/kernel/sched_domain/*
/proc/sys/kernel/sched_domain/cpu0:
domain0
/proc/sys/kernel/sched_domain/cpu1:
domain0
-Tommi