On my smp platform which is made of 5 cores in 2 clusters,I have the nr_busy_cpu field of sched_group_power struct that is not null when the platform is fully idle. The root cause seems to be: During the boot sequence, some CPUs reach the idle loop and set their NOHZ_IDLE flag while waiting for others CPUs to boot. But the nr_busy_cpus field is initialized later with the assumption that all CPUs are in the busy state whereas some CPUs have already set their NOHZ_IDLE flag. We clear the NOHZ_IDLE flag when nr_busy_cpus is initialized in order to have a coherent configuration.
Signed-off-by: Vincent Guittot vincent.guittot@linaro.org --- kernel/sched/core.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5dae0d2..05058e8 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5817,6 +5817,7 @@ static void init_sched_groups_power(int cpu, struct sched_domain *sd)
update_group_power(sd, cpu); atomic_set(&sg->sgp->nr_busy_cpus, sg->group_weight); + clear_bit(NOHZ_IDLE, nohz_flags(cpu)); }
int __weak arch_sd_sibling_asym_packing(void)