diff options
| -rw-r--r-- | kernel/sched.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 77c07c2928b9..e75b301b5340 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4712,6 +4712,57 @@ static void sched_domain_debug(struct sched_domain *sd, int cpu) #define sched_domain_debug(sd, cpu) {} #endif +static int __devinit sd_degenerate(struct sched_domain *sd) +{ + if (cpus_weight(sd->span) == 1) + return 1; + + /* Following flags need at least 2 groups */ + if (sd->flags & (SD_LOAD_BALANCE | + SD_BALANCE_NEWIDLE | + SD_BALANCE_FORK | + SD_BALANCE_EXEC)) { + if (sd->groups != sd->groups->next) + return 0; + } + + /* Following flags don't use groups */ + if (sd->flags & (SD_WAKE_IDLE | + SD_WAKE_AFFINE | + SD_WAKE_BALANCE)) + return 0; + + return 1; +} + +static int __devinit sd_parent_degenerate(struct sched_domain *sd, + struct sched_domain *parent) +{ + unsigned long cflags = sd->flags, pflags = parent->flags; + + if (sd_degenerate(parent)) + return 1; + + if (!cpus_equal(sd->span, parent->span)) + return 0; + + /* Does parent contain flags not in child? */ + /* WAKE_BALANCE is a subset of WAKE_AFFINE */ + if (cflags & SD_WAKE_AFFINE) + pflags &= ~SD_WAKE_BALANCE; + /* Flags needing groups don't count if only 1 group in parent */ + if (parent->groups == parent->groups->next) { + pflags &= ~(SD_LOAD_BALANCE | + SD_BALANCE_NEWIDLE | + SD_BALANCE_FORK | + SD_BALANCE_EXEC); + } + if (~cflags & pflags) + return 0; + + return 1; +} + /* * Attach the domain 'sd' to 'cpu' as its base domain. Callers must * hold the hotplug lock. @@ -4722,6 +4773,19 @@ void __devinit cpu_attach_domain(struct sched_domain *sd, int cpu) unsigned long flags; runqueue_t *rq = cpu_rq(cpu); int local = 1; + struct sched_domain *tmp; + + /* Remove the sched domains which do not contribute to scheduling. */ + for (tmp = sd; tmp; tmp = tmp->parent) { + struct sched_domain *parent = tmp->parent; + if (!parent) + break; + if (sd_parent_degenerate(tmp, parent)) + tmp->parent = parent->parent; + } + + if (sd && sd_degenerate(sd)) + sd = sd->parent; sched_domain_debug(sd, cpu); |