Asymmetric scheduling within a core is a scheduler loadbalancing
feature that is triggered when SD_ASYM_PACKING flag is set. The goal
for the load balancer is to move tasks to lower order idle SMT threads
within a core on a POWER7 system.
In nohz_kick_needed(), we intend to check if our sched domain (core)
is completely busy or we have idle cpu.
The following check for SD_ASYM_PACKING:
(cpumask_first_and(nohz.idle_cpus_mask, sched_domain_span(sd)) < cpu)
already covers the case of checking if the domain has an idle cpu,
because cpumask_first_and() will not yield any set bits if this domain
has no idle cpu.
Hence, nr_busy check against group weight can be removed.
Reported-by: Michael Neuling <michael.neul...@au1.ibm.com>
Signed-off-by: Vaidyanathan Srinivasan <sva...@linux.vnet.ibm.com>
Signed-off-by: Preeti U Murthy <pre...@linux.vnet.ibm.com>
---
kernel/sched/fair.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 12f0eab..828ed97 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5821,8 +5821,8 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu)
goto need_kick_unlock;
}
- if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
- && (cpumask_first_and(nohz.idle_cpus_mask,
+ if (sd->flags & SD_ASYM_PACKING &&
+ (cpumask_first_and(nohz.idle_cpus_mask,
sched_domain_span(sd)) < cpu))
goto need_kick_unlock;
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
