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Message-ID: <193b0f821003092118q4c7c18fds8b2ac4bacc91b475@mail.gmail.com>
Date: Wed, 10 Mar 2010 02:18:50 -0300
From: Lucas De Marchi <lucas.de.marchi@...il.com>
To: mingo@...e.hu, peterz@...radead.org
Cc: linux-kernel@...r.kernel.org,
Lucas De Marchi <lucas.de.marchi@...il.com>
Subject: Re: [PATCH] Group scheduler statistics in one struct
On Wed, Mar 10, 2010 at 02:07, Lucas De Marchi
<lucas.de.marchi@...il.com> wrote:
>
> From: Lucas De Marchi <lucas.de.marchi@...il.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@...il.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.
> 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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