According to the packing policy, the scheduler can pack tasks at different step: -SCHED_PACKING_NONE level: we don't pack any task. -SCHED_PACKING_DEFAULT: we only pack small tasks at wake up when system is not busy. -SCHED_PACKING_FULL: we pack tasks at wake up until a CPU becomes full. During a fork or a exec, we assume that the new task is a full running one and we look for an idle CPU close to the buddy CPU.
Signed-off-by: Vincent Guittot <[email protected]> --- kernel/sched/fair.c | 47 ++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 42 insertions(+), 5 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 98166aa..874f330 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3259,13 +3259,16 @@ static struct sched_group * find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu, int load_idx) { - struct sched_group *idlest = NULL, *group = sd->groups; + struct sched_group *idlest = NULL, *group = sd->groups, *buddy = NULL; unsigned long min_load = ULONG_MAX, this_load = 0; int imbalance = 100 + (sd->imbalance_pct-100)/2; + int buddy_cpu = per_cpu(sd_pack_buddy, this_cpu); + int get_buddy = ((sysctl_sched_packing_mode == SCHED_PACKING_FULL) && + !(sd->flags & SD_SHARE_POWERDOMAIN) && (buddy_cpu != -1)); do { unsigned long load, avg_load; - int local_group; + int local_group, buddy_group = 0; int i; /* Skip over this group if it has no CPUs allowed */ @@ -3276,6 +3279,11 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, local_group = cpumask_test_cpu(this_cpu, sched_group_cpus(group)); + if (get_buddy) { + buddy_group = cpumask_test_cpu(buddy_cpu, + sched_group_cpus(group)); + } + /* Tally up the load of all CPUs in the group */ avg_load = 0; @@ -3287,6 +3295,9 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, load = target_load(i, load_idx); avg_load += load; + + if ((buddy_group) && idle_cpu(i)) + buddy = group; } /* Adjust by relative CPU power of the group */ @@ -3300,6 +3311,9 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, } } while (group = group->next, group != sd->groups); + if (buddy) + return buddy; + if (!idlest || 100*this_load < imbalance*min_load) return NULL; return idlest; @@ -3402,6 +3416,21 @@ static bool is_buddy_busy(int cpu) return (sum > (period / (rq->nr_running + 2))); } +static bool is_buddy_full(int cpu) +{ + struct rq *rq = cpu_rq(cpu); + u32 sum = rq->avg.runnable_avg_sum; + u32 period = rq->avg.runnable_avg_period; + + sum = min(sum, period); + + /* + * A full buddy is a CPU with a sum greater or equal to period + * We keep a margin of 2.4% + */ + return (sum * 1024 >= period * 1000); +} + static bool is_light_task(struct task_struct *p) { /* A light task runs less than 20% in average */ @@ -3413,6 +3442,9 @@ static int check_pack_buddy(int cpu, struct task_struct *p) { int buddy = per_cpu(sd_pack_buddy, cpu); + if (sysctl_sched_packing_mode == SCHED_PACKING_NONE) + return false; + /* No pack buddy for this CPU */ if (buddy == -1) return false; @@ -3421,14 +3453,19 @@ static int check_pack_buddy(int cpu, struct task_struct *p) if (!cpumask_test_cpu(buddy, tsk_cpus_allowed(p))) return false; + /* We agressively pack at wake up */ + if ((sysctl_sched_packing_mode == SCHED_PACKING_FULL) + && !is_buddy_full(buddy)) + return true; /* * If the task is a small one and the buddy is not overloaded, * we use buddy cpu */ - if (!is_light_task(p) || is_buddy_busy(buddy)) - return false; + if (is_light_task(p) && !is_buddy_busy(buddy)) + return true; + + return false; - return true; } /* -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
