Messages in this thread Patch in this message | | | From | Vaidyanathan Srinivasan <> | Subject | [RFC PATCH v2 1/5] sched: load calculation for each group in sched domain | Date | Thu, 09 Oct 2008 17:39:25 +0530 |
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Add data structures for per group stats, and function to calculate the required per group stats.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> ---
kernel/sched.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 114 insertions(+), 0 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c index ad1962d..ab77937 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -3064,6 +3064,120 @@ static int move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest, return 0; } +/* Helper functions for find_busiest_group */ + +int get_load_idx(struct sched_domain *sd, enum cpu_idle_type idle) +{ + if (idle == CPU_NOT_IDLE) + return sd->busy_idx; + else if (idle == CPU_NEWLY_IDLE) + return sd->newidle_idx; + else + return sd->idle_idx; +} + +/* Struct to return group stats */ + +struct group_loads { + struct sched_group *group; + unsigned long nr_running; + unsigned long load; /* Decay average load */ + unsigned long load_per_cpu; /* Decay load / cpu_power */ + unsigned long weighted_load; /* Instantaneous load (load.weight)*/ + unsigned long avg_load_per_task; /* Instantaneous load/ nr_running */ + unsigned int group_imbalance; + int local_group; + int balance_cpu; +}; + +/* Helper function to calculate basic group level stats */ + +int get_group_loads(struct sched_group *group, int this_cpu, + const cpumask_t *valid_cpus, enum cpu_idle_type idle, + int load_idx, + struct group_loads *gl) +{ + struct rq *rq; + unsigned long load, min_load, max_load, avg_load_per_task_per_cpu; + int cpu; + int local_group = 0; + int first_idle_cpu = -1; + int need_balance = 1; + + gl->group = group; + gl->nr_running = 0; + gl->load = 0; + gl->weighted_load = 0; + gl->avg_load_per_task = 0; + gl->group_imbalance = 0; + gl->balance_cpu = -1; + max_load = 0; + min_load = ~0UL; + + gl->local_group = cpu_isset(this_cpu, group->cpumask); + + for_each_cpu_mask_nr(cpu, group->cpumask) { + if (!cpu_isset(cpu, *valid_cpus)) + continue; + + rq = cpu_rq(cpu); + + /* Bias balancing toward cpus of our domain */ + if (gl->local_group) { + if (idle_cpu(cpu) && first_idle_cpu == -1) + first_idle_cpu = cpu; + + load = target_load(cpu, load_idx); + } else { + load = source_load(cpu, load_idx); + if (load > max_load) + max_load = load; + if (load < min_load) + min_load = load; + } + gl->nr_running += rq->nr_running; + gl->load += load; + gl->weighted_load += weighted_cpuload(cpu); + gl->avg_load_per_task += cpu_avg_load_per_task(cpu); + } + + /* + * Consider the group unbalanced when the imbalance is larger + * than the average weight of two tasks. + * + * APZ: with cgroup the avg task weight can vary wildly and + * might not be a suitable number - should we keep a + * normalized nr_running number somewhere that negates + * the hierarchy? + */ + + avg_load_per_task_per_cpu = sg_div_cpu_power(group, + gl->avg_load_per_task * SCHED_LOAD_SCALE); + + if (!gl->local_group && + ((max_load - min_load) > 2*avg_load_per_task_per_cpu)) + gl->group_imbalance = 1; + + if (local_group) { + if (first_idle_cpu != -1) + gl->balance_cpu = first_idle_cpu; + else + gl->balance_cpu = first_cpu(group->cpumask); + + /* + * First idle cpu or the first cpu(busiest) in this sched group + * is eligible for doing load balancing at this and above + * domains. In the newly idle case, we will allow all the cpu's + * to do the newly idle load balance. + */ + if (idle != CPU_NEWLY_IDLE && gl->balance_cpu != this_cpu) + need_balance = 0; + } + gl->load_per_cpu = sg_div_cpu_power(group, gl->load * SCHED_LOAD_SCALE); + + return need_balance; +} + /* * find_busiest_group finds and returns the busiest CPU group within the * domain. It calculates and returns the amount of weighted load which
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