On Wed, Mar 10, 2010 at 02:18, Lucas De Marchi
<lucas.de.marchi@gmail.com> wrote:
quoted text
> On Wed, Mar 10, 2010 at 02:07, Lucas De Marchi
> <lucas.de.marchi@gmail.com> wrote:
>>
>> From: Lucas De Marchi <lucas.de.marchi@gmail.com>
>>
>> Put all statistic fields of sched_entity in one struct, sched_statistics,
>> and embed it into sched_entity.
>>
>> This change allows to memset the sched_statistics to 0 when needed (for
>> instance when forking), avoiding bugs of non initialized fields.
>>
>> Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
>> ---
>>  include/linux/sched.h |   54 ++++++++++++--------------
>>  kernel/sched.c        |   47 ++++------------------
>>  kernel/sched_debug.c  |  101 ++++++++++++++++++------------------------------
>>  kernel/sched_fair.c   |   65 ++++++++++++++++---------------
>>  kernel/sched_rt.c     |    2 +-
>>  5 files changed, 106 insertions(+), 163 deletions(-)
>>
>
> This patch is sitting on my .31's tree for quite a time. Today on
> checking out .34 I've seen there were new fields introduced by
> 8f0dfc34 "sched: Provide iowait counters" that were not properly
> initialized upon task fork ( __sched_fork()). Since this is not the
> first time this happens with these fields, I think it's better to use
> an approach like the patch below.
>
>

And of course this does not work because it has a typo and I forgot to
test with SCHED_DEBUG enabled. I'm sending the right version in a
following email.

Lucas De Marchi
quoted text
>
>> diff --git a/include/linux/sched.h b/include/linux/sched.h
>> index 46c6f8d..909e630 100644
>> --- a/include/linux/sched.h
>> +++ b/include/linux/sched.h
>> @@ -1073,36 +1073,8 @@ struct load_weight {
>>        unsigned long weight, inv_weight;
>>  };
>>
>> -/*
>> - * CFS stats for a schedulable entity (task, task-group etc)
>> - *
>> - * Current field usage histogram:
>> - *
>> - *     4 se->block_start
>> - *     4 se->run_node
>> - *     4 se->sleep_start
>> - *     6 se->load.weight
>> - */
>> -struct sched_entity {
>> -       struct load_weight      load;           /* for load-balancing */
>> -       struct rb_node          run_node;
>> -       struct list_head        group_node;
>> -       unsigned int            on_rq;
>> -
>> -       u64                     exec_start;
>> -       u64                     sum_exec_runtime;
>> -       u64                     vruntime;
>> -       u64                     prev_sum_exec_runtime;
>> -
>> -       u64                     last_wakeup;
>> -       u64                     avg_overlap;
>> -
>> -       u64                     nr_migrations;
>> -
>> -       u64                     start_runtime;
>> -       u64                     avg_wakeup;
>> -
>>  #ifdef CONFIG_SCHEDSTATS
>> +struct sched_statistics {
>>        u64                     wait_start;
>>        u64                     wait_max;
>>        u64                     wait_count;
>> @@ -1134,6 +1106,30 @@ struct sched_entity {
>>        u64                     nr_wakeups_affine_attempts;
>>        u64                     nr_wakeups_passive;
>>        u64                     nr_wakeups_idle;
>> +};
>> +#endif
>> +
>> +struct sched_entity {
>> +       struct load_weight      load;           /* for load-balancing */
>> +       struct rb_node          run_node;
>> +       struct list_head        group_node;
>> +       unsigned int            on_rq;
>> +
>> +       u64                     exec_start;
>> +       u64                     sum_exec_runtime;
>> +       u64                     vruntime;
>> +       u64                     prev_sum_exec_runtime;
>> +
>> +       u64                     last_wakeup;
>> +       u64                     avg_overlap;
>> +
>> +       u64                     nr_migrations;
>> +
>> +       u64                     start_runtime;
>> +       u64                     avg_wakeup;
>> +
>> +#ifdef CONFIG_SCHEDSTATS
>> +       struct sched_statistics statistics;
>>  #endif
>>
>>  #ifdef CONFIG_FAIR_GROUP_SCHED
>> diff --git a/kernel/sched.c b/kernel/sched.c
>> index 150b698..35c6b8a 100644
>> --- a/kernel/sched.c
>> +++ b/kernel/sched.c
>> @@ -2437,15 +2437,15 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
>>
>>  out_activate:
>>  #endif /* CONFIG_SMP */
>> -       schedstat_inc(p, se.nr_wakeups);
>> +       schedstat_inc(p, se.statistics.nr_wakeups);
>>        if (wake_flags & WF_SYNC)
>> -               schedstat_inc(p, se.nr_wakeups_sync);
>> +               schedstat_inc(p, se.statistics.nr_wakeups_sync);
>>        if (orig_cpu != cpu)
>> -               schedstat_inc(p, se.nr_wakeups_migrate);
>> +               schedstat_inc(p, se.statistics.nr_wakeups_migrate);
>>        if (cpu == this_cpu)
>> -               schedstat_inc(p, se.nr_wakeups_local);
>> +               schedstat_inc(p, se.statistics.nr_wakeups_local);
>>        else
>> -               schedstat_inc(p, se.nr_wakeups_remote);
>> +               schedstat_inc(p, se.statistics.nr_wakeups_remote);
>>        activate_task(rq, p, 1);
>>        success = 1;
>>
>> @@ -2532,36 +2532,7 @@ static void __sched_fork(struct task_struct *p)
>>        p->se.avg_wakeup                = sysctl_sched_wakeup_granularity;
>>
>>  #ifdef CONFIG_SCHEDSTATS
>> -       p->se.wait_start                        = 0;
>> -       p->se.wait_max                          = 0;
>> -       p->se.wait_count                        = 0;
>> -       p->se.wait_sum                          = 0;
>> -
>> -       p->se.sleep_start                       = 0;
>> -       p->se.sleep_max                         = 0;
>> -       p->se.sum_sleep_runtime                 = 0;
>> -
>> -       p->se.block_start                       = 0;
>> -       p->se.block_max                         = 0;
>> -       p->se.exec_max                          = 0;
>> -       p->se.slice_max                         = 0;
>> -
>> -       p->se.nr_migrations_cold                = 0;
>> -       p->se.nr_failed_migrations_affine       = 0;
>> -       p->se.nr_failed_migrations_running      = 0;
>> -       p->se.nr_failed_migrations_hot          = 0;
>> -       p->se.nr_forced_migrations              = 0;
>> -
>> -       p->se.nr_wakeups                        = 0;
>> -       p->se.nr_wakeups_sync                   = 0;
>> -       p->se.nr_wakeups_migrate                = 0;
>> -       p->se.nr_wakeups_local                  = 0;
>> -       p->se.nr_wakeups_remote                 = 0;
>> -       p->se.nr_wakeups_affine                 = 0;
>> -       p->se.nr_wakeups_affine_attempts        = 0;
>> -       p->se.nr_wakeups_passive                = 0;
>> -       p->se.nr_wakeups_idle                   = 0;
>> -
>> +       memset(&p->se.statistics, 0, sizeof(p->se.statistics));
>>  #endif
>>
>>        INIT_LIST_HEAD(&p->rt.run_list);
>> @@ -7914,9 +7885,9 @@ void normalize_rt_tasks(void)
>>
>>                p->se.exec_start                = 0;
>>  #ifdef CONFIG_SCHEDSTATS
>> -               p->se.wait_start                = 0;
>> -               p->se.sleep_start               = 0;
>> -               p->se.block_start               = 0;
>> +               p->se.statistics.wait_start     = 0;
>> +               p->se.statistics.sleep_start    = 0;
>> +               p->se.statistics.block_start    = 0;
>>  #endif
>>
>>                if (!rt_task(p)) {
>> diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
>> index 67f95aa..f6e8ed6 100644
>> --- a/kernel/sched_debug.c
>> +++ b/kernel/sched_debug.c
>> @@ -70,16 +70,16 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu,
>>        PN(se->vruntime);
>>        PN(se->sum_exec_runtime);
>>  #ifdef CONFIG_SCHEDSTATS
>> -       PN(se->wait_start);
>> -       PN(se->sleep_start);
>> -       PN(se->block_start);
>> -       PN(se->sleep_max);
>> -       PN(se->block_max);
>> -       PN(se->exec_max);
>> -       PN(se->slice_max);
>> -       PN(se->wait_max);
>> -       PN(se->wait_sum);
>> -       P(se->wait_count);
>> +       PN(se->statistiscs.wait_start);
>> +       PN(se->statistiscs.sleep_start);
>> +       PN(se->statistiscs.block_start);
>> +       PN(se->statistiscs.sleep_max);
>> +       PN(se->statistiscs.block_max);
>> +       PN(se->statistiscs.exec_max);
>> +       PN(se->statistiscs.slice_max);
>> +       PN(se->statistiscs.wait_max);
>> +       PN(se->statistiscs.wait_sum);
>> +       P(se->statistiscs.wait_count);
>>  #endif
>>        P(se->load.weight);
>>  #undef PN
>> @@ -104,7 +104,7 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
>>        SEQ_printf(m, "%9Ld.%06ld %9Ld.%06ld %9Ld.%06ld",
>>                SPLIT_NS(p->se.vruntime),
>>                SPLIT_NS(p->se.sum_exec_runtime),
>> -               SPLIT_NS(p->se.sum_sleep_runtime));
>> +               SPLIT_NS(p->se.statistics.sum_sleep_runtime));
>>  #else
>>        SEQ_printf(m, "%15Ld %15Ld %15Ld.%06ld %15Ld.%06ld %15Ld.%06ld",
>>                0LL, 0LL, 0LL, 0L, 0LL, 0L, 0LL, 0L);
>> @@ -413,34 +413,34 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
>>        nr_switches = p->nvcsw + p->nivcsw;
>>
>>  #ifdef CONFIG_SCHEDSTATS
>> -       PN(se.wait_start);
>> -       PN(se.sleep_start);
>> -       PN(se.block_start);
>> -       PN(se.sleep_max);
>> -       PN(se.block_max);
>> -       PN(se.exec_max);
>> -       PN(se.slice_max);
>> -       PN(se.wait_max);
>> -       PN(se.wait_sum);
>> -       P(se.wait_count);
>> -       PN(se.iowait_sum);
>> -       P(se.iowait_count);
>> +       PN(se.statistiscs.wait_start);
>> +       PN(se.statistiscs.sleep_start);
>> +       PN(se.statistiscs.block_start);
>> +       PN(se.statistiscs.sleep_max);
>> +       PN(se.statistiscs.block_max);
>> +       PN(se.statistiscs.exec_max);
>> +       PN(se.statistiscs.slice_max);
>> +       PN(se.statistiscs.wait_max);
>> +       PN(se.statistiscs.wait_sum);
>> +       P(se.statistiscs.wait_count);
>> +       PN(se.statistiscs.iowait_sum);
>> +       P(se.statistiscs.iowait_count);
>>        P(sched_info.bkl_count);
>>        P(se.nr_migrations);
>> -       P(se.nr_migrations_cold);
>> -       P(se.nr_failed_migrations_affine);
>> -       P(se.nr_failed_migrations_running);
>> -       P(se.nr_failed_migrations_hot);
>> -       P(se.nr_forced_migrations);
>> -       P(se.nr_wakeups);
>> -       P(se.nr_wakeups_sync);
>> -       P(se.nr_wakeups_migrate);
>> -       P(se.nr_wakeups_local);
>> -       P(se.nr_wakeups_remote);
>> -       P(se.nr_wakeups_affine);
>> -       P(se.nr_wakeups_affine_attempts);
>> -       P(se.nr_wakeups_passive);
>> -       P(se.nr_wakeups_idle);
>> +       P(se.statistiscs.nr_migrations_cold);
>> +       P(se.statistiscs.nr_failed_migrations_affine);
>> +       P(se.statistiscs.nr_failed_migrations_running);
>> +       P(se.statistiscs.nr_failed_migrations_hot);
>> +       P(se.statistiscs.nr_forced_migrations);
>> +       P(se.statistiscs.nr_wakeups);
>> +       P(se.statistiscs.nr_wakeups_sync);
>> +       P(se.statistiscs.nr_wakeups_migrate);
>> +       P(se.statistiscs.nr_wakeups_local);
>> +       P(se.statistiscs.nr_wakeups_remote);
>> +       P(se.statistiscs.nr_wakeups_affine);
>> +       P(se.statistiscs.nr_wakeups_affine_attempts);
>> +       P(se.statistiscs.nr_wakeups_passive);
>> +       P(se.statistiscs.nr_wakeups_idle);
>>
>>        {
>>                u64 avg_atom, avg_per_cpu;
>> @@ -491,32 +491,7 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
>>  void proc_sched_set_task(struct task_struct *p)
>>  {
>>  #ifdef CONFIG_SCHEDSTATS
>> -       p->se.wait_max                          = 0;
>> -       p->se.wait_sum                          = 0;
>> -       p->se.wait_count                        = 0;
>> -       p->se.iowait_sum                        = 0;
>> -       p->se.iowait_count                      = 0;
>> -       p->se.sleep_max                         = 0;
>> -       p->se.sum_sleep_runtime                 = 0;
>> -       p->se.block_max                         = 0;
>> -       p->se.exec_max                          = 0;
>> -       p->se.slice_max                         = 0;
>> -       p->se.nr_migrations                     = 0;
>> -       p->se.nr_migrations_cold                = 0;
>> -       p->se.nr_failed_migrations_affine       = 0;
>> -       p->se.nr_failed_migrations_running      = 0;
>> -       p->se.nr_failed_migrations_hot          = 0;
>> -       p->se.nr_forced_migrations              = 0;
>> -       p->se.nr_wakeups                        = 0;
>> -       p->se.nr_wakeups_sync                   = 0;
>> -       p->se.nr_wakeups_migrate                = 0;
>> -       p->se.nr_wakeups_local                  = 0;
>> -       p->se.nr_wakeups_remote                 = 0;
>> -       p->se.nr_wakeups_affine                 = 0;
>> -       p->se.nr_wakeups_affine_attempts        = 0;
>> -       p->se.nr_wakeups_passive                = 0;
>> -       p->se.nr_wakeups_idle                   = 0;
>> -       p->sched_info.bkl_count                 = 0;
>> +       memset(&p->se.statistics, 0, sizeof(p->se.statistics));
>>  #endif
>>        p->se.sum_exec_runtime                  = 0;
>>        p->se.prev_sum_exec_runtime             = 0;
>> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
>> index 3e1fd96..8ad164b 100644
>> --- a/kernel/sched_fair.c
>> +++ b/kernel/sched_fair.c
>> @@ -505,7 +505,8 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
>>  {
>>        unsigned long delta_exec_weighted;
>>
>> -       schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
>> +       schedstat_set(curr->statistics.exec_max,
>> +                     max((u64)delta_exec, curr->statistics.exec_max));
>>
>>        curr->sum_exec_runtime += delta_exec;
>>        schedstat_add(cfs_rq, exec_clock, delta_exec);
>> @@ -548,7 +549,7 @@ static void update_curr(struct cfs_rq *cfs_rq)
>>  static inline void
>>  update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
>>  {
>> -       schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
>> +       schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock);
>>  }
>>
>>  /*
>> @@ -567,18 +568,18 @@ static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
>>  static void
>>  update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
>>  {
>> -       schedstat_set(se->wait_max, max(se->wait_max,
>> -                       rq_of(cfs_rq)->clock - se->wait_start));
>> -       schedstat_set(se->wait_count, se->wait_count + 1);
>> -       schedstat_set(se->wait_sum, se->wait_sum +
>> -                       rq_of(cfs_rq)->clock - se->wait_start);
>> +       schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max,
>> +                       rq_of(cfs_rq)->clock - se->statistics.wait_start));
>> +       schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1);
>> +       schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum +
>> +                       rq_of(cfs_rq)->clock - se->statistics.wait_start);
>>  #ifdef CONFIG_SCHEDSTATS
>>        if (entity_is_task(se)) {
>>                trace_sched_stat_wait(task_of(se),
>> -                       rq_of(cfs_rq)->clock - se->wait_start);
>> +                       rq_of(cfs_rq)->clock - se->statistics.wait_start);
>>        }
>>  #endif
>> -       schedstat_set(se->wait_start, 0);
>> +       schedstat_set(se->statistics.wait_start, 0);
>>  }
>>
>>  static inline void
>> @@ -657,39 +658,39 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
>>        if (entity_is_task(se))
>>                tsk = task_of(se);
>>
>> -       if (se->sleep_start) {
>> -               u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
>> +       if (se->statistics.sleep_start) {
>> +               u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start;
>>
>>                if ((s64)delta < 0)
>>                        delta = 0;
>>
>> -               if (unlikely(delta > se->sleep_max))
>> -                       se->sleep_max = delta;
>> +               if (unlikely(delta > se->statistics.sleep_max))
>> +                       se->statistics.sleep_max = delta;
>>
>> -               se->sleep_start = 0;
>> -               se->sum_sleep_runtime += delta;
>> +               se->statistics.sleep_start = 0;
>> +               se->statistics.sum_sleep_runtime += delta;
>>
>>                if (tsk) {
>>                        account_scheduler_latency(tsk, delta >> 10, 1);
>>                        trace_sched_stat_sleep(tsk, delta);
>>                }
>>        }
>> -       if (se->block_start) {
>> -               u64 delta = rq_of(cfs_rq)->clock - se->block_start;
>> +       if (se->statistics.block_start) {
>> +               u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start;
>>
>>                if ((s64)delta < 0)
>>                        delta = 0;
>>
>> -               if (unlikely(delta > se->block_max))
>> -                       se->block_max = delta;
>> +               if (unlikely(delta > se->statistics.block_max))
>> +                       se->statistics.block_max = delta;
>>
>> -               se->block_start = 0;
>> -               se->sum_sleep_runtime += delta;
>> +               se->statistics.block_start = 0;
>> +               se->statistics.sum_sleep_runtime += delta;
>>
>>                if (tsk) {
>>                        if (tsk->in_iowait) {
>> -                               se->iowait_sum += delta;
>> -                               se->iowait_count++;
>> +                               se->statistics.iowait_sum += delta;
>> +                               se->statistics.iowait_count++;
>>                                trace_sched_stat_iowait(tsk, delta);
>>                        }
>>
>> @@ -826,9 +827,9 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
>>                        struct task_struct *tsk = task_of(se);
>>
>>                        if (tsk->state & TASK_INTERRUPTIBLE)
>> -                               se->sleep_start = rq_of(cfs_rq)->clock;
>> +                               se->statistics.sleep_start = rq_of(cfs_rq)->clock;
>>                        if (tsk->state & TASK_UNINTERRUPTIBLE)
>> -                               se->block_start = rq_of(cfs_rq)->clock;
>> +                               se->statistics.block_start = rq_of(cfs_rq)->clock;
>>                }
>>  #endif
>>        }
>> @@ -912,7 +913,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
>>         * when there are only lesser-weight tasks around):
>>         */
>>        if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
>> -               se->slice_max = max(se->slice_max,
>> +               se->statistics.slice_max = max(se->statistics.slice_max,
>>                        se->sum_exec_runtime - se->prev_sum_exec_runtime);
>>        }
>>  #endif
>> @@ -1306,7 +1307,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
>>        if (sync && balanced)
>>                return 1;
>>
>> -       schedstat_inc(p, se.nr_wakeups_affine_attempts);
>> +       schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
>>        tl_per_task = cpu_avg_load_per_task(this_cpu);
>>
>>        if (balanced ||
>> @@ -1318,7 +1319,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
>>                 * there is no bad imbalance.
>>                 */
>>                schedstat_inc(sd, ttwu_move_affine);
>> -               schedstat_inc(p, se.nr_wakeups_affine);
>> +               schedstat_inc(p, se.statistics.nr_wakeups_affine);
>>
>>                return 1;
>>        }
>> @@ -1844,13 +1845,13 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
>>         * 3) are cache-hot on their current CPU.
>>         */
>>        if (!cpumask_test_cpu(this_cpu, &p->cpus_allowed)) {
>> -               schedstat_inc(p, se.nr_failed_migrations_affine);
>> +               schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
>>                return 0;
>>        }
>>        *all_pinned = 0;
>>
>>        if (task_running(rq, p)) {
>> -               schedstat_inc(p, se.nr_failed_migrations_running);
>> +               schedstat_inc(p, se.statistics.nr_failed_migrations_running);
>>                return 0;
>>        }
>>
>> @@ -1866,14 +1867,14 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
>>  #ifdef CONFIG_SCHEDSTATS
>>                if (tsk_cache_hot) {
>>                        schedstat_inc(sd, lb_hot_gained[idle]);
>> -                       schedstat_inc(p, se.nr_forced_migrations);
>> +                       schedstat_inc(p, se.statistics.nr_forced_migrations);
>>                }
>>  #endif
>>                return 1;
>>        }
>>
>>        if (tsk_cache_hot) {
>> -               schedstat_inc(p, se.nr_failed_migrations_hot);
>> +               schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
>>                return 0;
>>        }
>>        return 1;
>> diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
>> index 5a6ed1f..47a121d 100644
>> --- a/kernel/sched_rt.c
>> +++ b/kernel/sched_rt.c
>> @@ -613,7 +613,7 @@ static void update_curr_rt(struct rq *rq)
>>        if (unlikely((s64)delta_exec < 0))
>>                delta_exec = 0;
>>
>> -       schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec));
>> +       schedstat_set(curr->se.statistics.exec_max, max(curr->se.statistics.exec_max, delta_exec));
>>
>>        curr->se.sum_exec_runtime += delta_exec;
>>        account_group_exec_runtime(curr, delta_exec);
>> --
>> 1.7.0.2
>>
>
--
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