If we want to use schedstats facility, we should move out of
struct sched_statistics from the struct sched_entity or add it into other
sctructs of sched entity as well. Obviously the latter one is bad because
that requires more spaces. So we should move it into a common struct which
can be used by all sched classes.
The struct sched_statistics is the schedular statistics of a task_struct
or a task_group. So we can move it into struct task_struct and
struct task_group to achieve the goal.
Below is the detailed explaination of the change in the structs.
- Before this patch
struct task_struct { |-> struct sched_entity {
... | ...
struct sched_entity *se; ---| struct sched_statistics statistics;
struct sched_rt_entity *rt; ...
... ...
}; };
struct task_group { |--> se[0]->statistics : schedstats of CPU0
... |
#ifdef CONFIG_FAIR_GROUP_SCHED |
struct sched_entity **se; --|--> se[1]->statistics : schedstats of CPU1
|
#endif |
|--> se[N]->statistics : schedstats of CPUn
#ifdef CONFIG_FAIR_GROUP_SCHED
struct sched_rt_entity **rt_se; (N/A)
#endif
...
};
The '**se' in task_group is allocated in the fair sched class, which is
hard to be reused by other sched class.
- After this patch
struct task_struct {
...
struct sched_statistics statistics;
...
struct sched_entity *se;
struct sched_rt_entity *rt;
...
};
struct task_group { |---> stats[0] : of CPU0
... |
struct sched_statistics **stats; --|---> stats[1] : of CPU1
... |
|---> stats[n] : of CPUn
#ifdef CONFIG_FAIR_GROUP_SCHED
struct sched_entity **se;
#endif
#ifdef CONFIG_RT_GROUP_SCHED
struct sched_rt_entity **rt_se;
#endif
...
};
After the patch it is clearly that both of se or rt_se can easily get the
sched_statistics by a task_struct or a task_group.
Signed-off-by: Yafang Shao <[email protected]>
---
include/linux/sched.h | 3 +-
kernel/sched/core.c | 24 ++++---
kernel/sched/deadline.c | 4 +-
kernel/sched/debug.c | 81 +++++++++++-----------
kernel/sched/fair.c | 142 ++++++++++++++++++++++++++-------------
kernel/sched/rt.c | 4 +-
kernel/sched/sched.h | 3 +
kernel/sched/stats.h | 46 +++++++++++++
kernel/sched/stop_task.c | 4 +-
9 files changed, 206 insertions(+), 105 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 063cd120b459..f8e969be4bee 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -462,8 +462,6 @@ struct sched_entity {
u64 nr_migrations;
- struct sched_statistics statistics;
-
#ifdef CONFIG_FAIR_GROUP_SCHED
int depth;
struct sched_entity *parent;
@@ -681,6 +679,7 @@ struct task_struct {
unsigned int rt_priority;
const struct sched_class *sched_class;
+ struct sched_statistics stats;
struct sched_entity se;
struct sched_rt_entity rt;
#ifdef CONFIG_CGROUP_SCHED
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fd76628778f7..081b4f1f2cb4 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2427,11 +2427,11 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
#ifdef CONFIG_SMP
if (cpu == rq->cpu) {
__schedstat_inc(rq->ttwu_local);
- __schedstat_inc(p->se.statistics.nr_wakeups_local);
+ __schedstat_inc(p->stats.nr_wakeups_local);
} else {
struct sched_domain *sd;
- __schedstat_inc(p->se.statistics.nr_wakeups_remote);
+ __schedstat_inc(p->stats.nr_wakeups_remote);
rcu_read_lock();
for_each_domain(rq->cpu, sd) {
if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
@@ -2443,14 +2443,14 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
}
if (wake_flags & WF_MIGRATED)
- __schedstat_inc(p->se.statistics.nr_wakeups_migrate);
+ __schedstat_inc(p->stats.nr_wakeups_migrate);
#endif /* CONFIG_SMP */
__schedstat_inc(rq->ttwu_count);
- __schedstat_inc(p->se.statistics.nr_wakeups);
+ __schedstat_inc(p->stats.nr_wakeups);
if (wake_flags & WF_SYNC)
- __schedstat_inc(p->se.statistics.nr_wakeups_sync);
+ __schedstat_inc(p->stats.nr_wakeups_sync);
}
/*
@@ -3075,7 +3075,7 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
#ifdef CONFIG_SCHEDSTATS
/* Even if schedstat is disabled, there should not be garbage */
- memset(&p->se.statistics, 0, sizeof(p->se.statistics));
+ memset(&p->stats, 0, sizeof(p->stats));
#endif
RB_CLEAR_NODE(&p->dl.rb_node);
@@ -7347,9 +7347,9 @@ void normalize_rt_tasks(void)
continue;
p->se.exec_start = 0;
- schedstat_set(p->se.statistics.wait_start, 0);
- schedstat_set(p->se.statistics.sleep_start, 0);
- schedstat_set(p->se.statistics.block_start, 0);
+ schedstat_set(p->stats.wait_start, 0);
+ schedstat_set(p->stats.sleep_start, 0);
+ schedstat_set(p->stats.block_start, 0);
if (!dl_task(p) && !rt_task(p)) {
/*
@@ -7439,6 +7439,7 @@ static void sched_free_group(struct task_group *tg)
{
free_fair_sched_group(tg);
free_rt_sched_group(tg);
+ free_tg_schedstats(tg);
autogroup_free(tg);
kmem_cache_free(task_group_cache, tg);
}
@@ -7458,6 +7459,9 @@ struct task_group *sched_create_group(struct task_group *parent)
if (!alloc_rt_sched_group(tg, parent))
goto err;
+ if (!alloc_tg_schedstats(tg))
+ goto err;
+
alloc_uclamp_sched_group(tg, parent);
return tg;
@@ -8144,7 +8148,7 @@ static int cpu_cfs_stat_show(struct seq_file *sf, void *v)
int i;
for_each_possible_cpu(i)
- ws += schedstat_val(tg->se[i]->statistics.wait_sum);
+ ws += schedstat_val(tg->stats[i]->wait_sum);
seq_printf(sf, "wait_sum %llu\n", ws);
}
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 7a0124f81a4f..315d140b8f0e 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1245,8 +1245,8 @@ static void update_curr_dl(struct rq *rq)
return;
}
- schedstat_set(curr->se.statistics.exec_max,
- max(curr->se.statistics.exec_max, delta_exec));
+ schedstat_set(curr->stats.exec_max,
+ max(curr->stats.exec_max, delta_exec));
curr->se.sum_exec_runtime += delta_exec;
account_group_exec_runtime(curr, delta_exec);
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 9758aa1bba1e..8c646fcb89de 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -444,16 +444,16 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
PN(se->sum_exec_runtime);
if (schedstat_enabled()) {
- PN_SCHEDSTAT(se->statistics.wait_start);
- PN_SCHEDSTAT(se->statistics.sleep_start);
- PN_SCHEDSTAT(se->statistics.block_start);
- PN_SCHEDSTAT(se->statistics.sleep_max);
- PN_SCHEDSTAT(se->statistics.block_max);
- PN_SCHEDSTAT(se->statistics.exec_max);
- PN_SCHEDSTAT(se->statistics.slice_max);
- PN_SCHEDSTAT(se->statistics.wait_max);
- PN_SCHEDSTAT(se->statistics.wait_sum);
- P_SCHEDSTAT(se->statistics.wait_count);
+ PN_SCHEDSTAT(tg->stats[cpu]->wait_start);
+ PN_SCHEDSTAT(tg->stats[cpu]->sleep_start);
+ PN_SCHEDSTAT(tg->stats[cpu]->block_start);
+ PN_SCHEDSTAT(tg->stats[cpu]->sleep_max);
+ PN_SCHEDSTAT(tg->stats[cpu]->block_max);
+ PN_SCHEDSTAT(tg->stats[cpu]->exec_max);
+ PN_SCHEDSTAT(tg->stats[cpu]->slice_max);
+ PN_SCHEDSTAT(tg->stats[cpu]->wait_max);
+ PN_SCHEDSTAT(tg->stats[cpu]->wait_sum);
+ P_SCHEDSTAT(tg->stats[cpu]->wait_count);
}
P(se->load.weight);
@@ -499,9 +499,9 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
p->prio);
SEQ_printf(m, "%9Ld.%06ld %9Ld.%06ld %9Ld.%06ld",
- SPLIT_NS(schedstat_val_or_zero(p->se.statistics.wait_sum)),
+ SPLIT_NS(schedstat_val_or_zero(p->stats.wait_sum)),
SPLIT_NS(p->se.sum_exec_runtime),
- SPLIT_NS(schedstat_val_or_zero(p->se.statistics.sum_sleep_runtime)));
+ SPLIT_NS(schedstat_val_or_zero(p->stats.sum_sleep_runtime)));
#ifdef CONFIG_NUMA_BALANCING
SEQ_printf(m, " %d %d", task_node(p), task_numa_group_id(p));
@@ -938,34 +938,33 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
if (schedstat_enabled()) {
u64 avg_atom, avg_per_cpu;
-
- PN_SCHEDSTAT(se.statistics.sum_sleep_runtime);
- PN_SCHEDSTAT(se.statistics.wait_start);
- PN_SCHEDSTAT(se.statistics.sleep_start);
- PN_SCHEDSTAT(se.statistics.block_start);
- PN_SCHEDSTAT(se.statistics.sleep_max);
- PN_SCHEDSTAT(se.statistics.block_max);
- PN_SCHEDSTAT(se.statistics.exec_max);
- PN_SCHEDSTAT(se.statistics.slice_max);
- PN_SCHEDSTAT(se.statistics.wait_max);
- PN_SCHEDSTAT(se.statistics.wait_sum);
- P_SCHEDSTAT(se.statistics.wait_count);
- PN_SCHEDSTAT(se.statistics.iowait_sum);
- P_SCHEDSTAT(se.statistics.iowait_count);
- P_SCHEDSTAT(se.statistics.nr_migrations_cold);
- P_SCHEDSTAT(se.statistics.nr_failed_migrations_affine);
- P_SCHEDSTAT(se.statistics.nr_failed_migrations_running);
- P_SCHEDSTAT(se.statistics.nr_failed_migrations_hot);
- P_SCHEDSTAT(se.statistics.nr_forced_migrations);
- P_SCHEDSTAT(se.statistics.nr_wakeups);
- P_SCHEDSTAT(se.statistics.nr_wakeups_sync);
- P_SCHEDSTAT(se.statistics.nr_wakeups_migrate);
- P_SCHEDSTAT(se.statistics.nr_wakeups_local);
- P_SCHEDSTAT(se.statistics.nr_wakeups_remote);
- P_SCHEDSTAT(se.statistics.nr_wakeups_affine);
- P_SCHEDSTAT(se.statistics.nr_wakeups_affine_attempts);
- P_SCHEDSTAT(se.statistics.nr_wakeups_passive);
- P_SCHEDSTAT(se.statistics.nr_wakeups_idle);
+ PN_SCHEDSTAT(stats.sum_sleep_runtime);
+ PN_SCHEDSTAT(stats.wait_start);
+ PN_SCHEDSTAT(stats.sleep_start);
+ PN_SCHEDSTAT(stats.block_start);
+ PN_SCHEDSTAT(stats.sleep_max);
+ PN_SCHEDSTAT(stats.block_max);
+ PN_SCHEDSTAT(stats.exec_max);
+ PN_SCHEDSTAT(stats.slice_max);
+ PN_SCHEDSTAT(stats.wait_max);
+ PN_SCHEDSTAT(stats.wait_sum);
+ P_SCHEDSTAT(stats.wait_count);
+ PN_SCHEDSTAT(stats.iowait_sum);
+ P_SCHEDSTAT(stats.iowait_count);
+ P_SCHEDSTAT(stats.nr_migrations_cold);
+ P_SCHEDSTAT(stats.nr_failed_migrations_affine);
+ P_SCHEDSTAT(stats.nr_failed_migrations_running);
+ P_SCHEDSTAT(stats.nr_failed_migrations_hot);
+ P_SCHEDSTAT(stats.nr_forced_migrations);
+ P_SCHEDSTAT(stats.nr_wakeups);
+ P_SCHEDSTAT(stats.nr_wakeups_sync);
+ P_SCHEDSTAT(stats.nr_wakeups_migrate);
+ P_SCHEDSTAT(stats.nr_wakeups_local);
+ P_SCHEDSTAT(stats.nr_wakeups_remote);
+ P_SCHEDSTAT(stats.nr_wakeups_affine);
+ P_SCHEDSTAT(stats.nr_wakeups_affine_attempts);
+ P_SCHEDSTAT(stats.nr_wakeups_passive);
+ P_SCHEDSTAT(stats.nr_wakeups_idle);
avg_atom = p->se.sum_exec_runtime;
if (nr_switches)
@@ -1031,6 +1030,6 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
void proc_sched_set_task(struct task_struct *p)
{
#ifdef CONFIG_SCHEDSTATS
- memset(&p->se.statistics, 0, sizeof(p->se.statistics));
+ memset(&p->stats, 0, sizeof(p->stats));
#endif
}
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7e7c03cede94..14d8df308d44 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -837,12 +837,44 @@ static void update_tg_load_avg(struct cfs_rq *cfs_rq)
}
#endif /* CONFIG_SMP */
+static inline void
+__schedstat_from_sched_entity(struct sched_entity *se,
+ struct sched_statistics **stats)
+{
+ struct task_struct *p;
+ struct task_group *tg;
+ struct cfs_rq *cfs_rq;
+ int cpu;
+
+ if (entity_is_task(se)) {
+ p = task_of(se);
+ *stats = &p->stats;
+ } else {
+ cfs_rq = group_cfs_rq(se);
+ tg = cfs_rq->tg;
+ cpu = cpu_of(rq_of(cfs_rq));
+ *stats = tg->stats[cpu];
+ }
+}
+
+static inline void
+schedstat_from_sched_entity(struct sched_entity *se,
+ struct sched_statistics **stats)
+{
+ if (!schedstat_enabled())
+ return;
+
+ __schedstat_from_sched_entity(se, stats);
+}
+
/*
* Update the current task's runtime statistics.
*/
static void update_curr(struct cfs_rq *cfs_rq)
{
struct sched_entity *curr = cfs_rq->curr;
+ struct sched_statistics *stats = NULL;
+
u64 now = rq_clock_task(rq_of(cfs_rq));
u64 delta_exec;
@@ -855,8 +887,12 @@ static void update_curr(struct cfs_rq *cfs_rq)
curr->exec_start = now;
- schedstat_set(curr->statistics.exec_max,
- max(delta_exec, curr->statistics.exec_max));
+ if (schedstat_enabled()) {
+ __schedstat_from_sched_entity(curr, &stats);
+
+ __schedstat_set(stats->exec_max,
+ max(delta_exec, stats->exec_max));
+ }
curr->sum_exec_runtime += delta_exec;
schedstat_add(cfs_rq->exec_clock, delta_exec);
@@ -883,67 +919,78 @@ static void update_curr_fair(struct rq *rq)
static inline void
update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
+ struct sched_statistics *stats = NULL;
u64 wait_start, prev_wait_start;
if (!schedstat_enabled())
return;
+ __schedstat_from_sched_entity(se, &stats);
+
wait_start = rq_clock(rq_of(cfs_rq));
- prev_wait_start = schedstat_val(se->statistics.wait_start);
+ prev_wait_start = schedstat_val(stats->wait_start);
if (entity_is_task(se) && task_on_rq_migrating(task_of(se)) &&
likely(wait_start > prev_wait_start))
wait_start -= prev_wait_start;
- __schedstat_set(se->statistics.wait_start, wait_start);
+ __schedstat_set(stats->wait_start, wait_start);
}
static inline void
update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- struct task_struct *p;
+ struct sched_statistics *stats = NULL;
+ struct task_struct *p = NULL;
u64 delta;
if (!schedstat_enabled())
return;
- delta = rq_clock(rq_of(cfs_rq)) - schedstat_val(se->statistics.wait_start);
+ __schedstat_from_sched_entity(se, &stats);
+ delta = rq_clock(rq_of(cfs_rq)) - schedstat_val(stats->wait_start);
if (entity_is_task(se)) {
p = task_of(se);
+
if (task_on_rq_migrating(p)) {
/*
* Preserve migrating task's wait time so wait_start
* time stamp can be adjusted to accumulate wait time
* prior to migration.
*/
- __schedstat_set(se->statistics.wait_start, delta);
+ __schedstat_set(stats->wait_start, delta);
+
return;
}
+
trace_sched_stat_wait(p, delta);
}
- __schedstat_set(se->statistics.wait_max,
- max(schedstat_val(se->statistics.wait_max), delta));
- __schedstat_inc(se->statistics.wait_count);
- __schedstat_add(se->statistics.wait_sum, delta);
- __schedstat_set(se->statistics.wait_start, 0);
+ __schedstat_set(stats->wait_max,
+ max(schedstat_val(stats->wait_max), delta));
+ __schedstat_inc(stats->wait_count);
+ __schedstat_add(stats->wait_sum, delta);
+ __schedstat_set(stats->wait_start, 0);
}
static inline void
update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- struct task_struct *tsk = NULL;
+ struct sched_statistics *stats = NULL;
+ struct task_struct *p = NULL;
u64 sleep_start, block_start;
if (!schedstat_enabled())
return;
- sleep_start = schedstat_val(se->statistics.sleep_start);
- block_start = schedstat_val(se->statistics.block_start);
-
if (entity_is_task(se))
- tsk = task_of(se);
+ p = task_of(se);
+
+ __schedstat_from_sched_entity(se, &stats);
+
+ sleep_start = schedstat_val(stats->sleep_start);
+ block_start = schedstat_val(stats->block_start);
if (sleep_start) {
u64 delta = rq_clock(rq_of(cfs_rq)) - sleep_start;
@@ -951,15 +998,15 @@ update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
if ((s64)delta < 0)
delta = 0;
- if (unlikely(delta > schedstat_val(se->statistics.sleep_max)))
- __schedstat_set(se->statistics.sleep_max, delta);
+ if (unlikely(delta > schedstat_val(stats->sleep_max)))
+ __schedstat_set(stats->sleep_max, delta);
- __schedstat_set(se->statistics.sleep_start, 0);
- __schedstat_add(se->statistics.sum_sleep_runtime, delta);
+ __schedstat_set(stats->sleep_start, 0);
+ __schedstat_add(stats->sum_sleep_runtime, delta);
- if (tsk) {
- account_scheduler_latency(tsk, delta >> 10, 1);
- trace_sched_stat_sleep(tsk, delta);
+ if (p) {
+ account_scheduler_latency(p, delta >> 10, 1);
+ trace_sched_stat_sleep(p, delta);
}
}
if (block_start) {
@@ -968,20 +1015,20 @@ update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
if ((s64)delta < 0)
delta = 0;
- if (unlikely(delta > schedstat_val(se->statistics.block_max)))
- __schedstat_set(se->statistics.block_max, delta);
+ if (unlikely(delta > schedstat_val(stats->block_max)))
+ __schedstat_set(stats->block_max, delta);
- __schedstat_set(se->statistics.block_start, 0);
- __schedstat_add(se->statistics.sum_sleep_runtime, delta);
+ __schedstat_set(stats->block_start, 0);
+ __schedstat_add(stats->sum_sleep_runtime, delta);
- if (tsk) {
- if (tsk->in_iowait) {
- __schedstat_add(se->statistics.iowait_sum, delta);
- __schedstat_inc(se->statistics.iowait_count);
- trace_sched_stat_iowait(tsk, delta);
+ if (p) {
+ if (p->in_iowait) {
+ __schedstat_add(stats->iowait_sum, delta);
+ __schedstat_inc(stats->iowait_count);
+ trace_sched_stat_iowait(p, delta);
}
- trace_sched_stat_blocked(tsk, delta);
+ trace_sched_stat_blocked(p, delta);
/*
* Blocking time is in units of nanosecs, so shift by
@@ -990,10 +1037,10 @@ update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
*/
if (unlikely(prof_on == SLEEP_PROFILING)) {
profile_hits(SLEEP_PROFILING,
- (void *)get_wchan(tsk),
+ (void *)get_wchan(p),
delta >> 20);
}
- account_scheduler_latency(tsk, delta >> 10, 0);
+ account_scheduler_latency(p, delta >> 10, 0);
}
}
}
@@ -1036,10 +1083,10 @@ update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
struct task_struct *tsk = task_of(se);
if (tsk->state & TASK_INTERRUPTIBLE)
- __schedstat_set(se->statistics.sleep_start,
+ __schedstat_set(tsk->stats.sleep_start,
rq_clock(rq_of(cfs_rq)));
if (tsk->state & TASK_UNINTERRUPTIBLE)
- __schedstat_set(se->statistics.block_start,
+ __schedstat_set(tsk->stats.block_start,
rq_clock(rq_of(cfs_rq)));
}
}
@@ -4392,6 +4439,8 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
static void
set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
+ struct sched_statistics *stats = NULL;
+
/* 'current' is not kept within the tree. */
if (se->on_rq) {
/*
@@ -4414,8 +4463,9 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
*/
if (schedstat_enabled() &&
rq_of(cfs_rq)->cfs.load.weight >= 2*se->load.weight) {
- __schedstat_set(se->statistics.slice_max,
- max((u64)schedstat_val(se->statistics.slice_max),
+ __schedstat_from_sched_entity(se, &stats);
+ __schedstat_set(stats->slice_max,
+ max((u64)schedstat_val(stats->slice_max),
se->sum_exec_runtime - se->prev_sum_exec_runtime));
}
@@ -5862,12 +5912,12 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p,
if (sched_feat(WA_WEIGHT) && target == nr_cpumask_bits)
target = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync);
- schedstat_inc(p->se.statistics.nr_wakeups_affine_attempts);
+ schedstat_inc(p->stats.nr_wakeups_affine_attempts);
if (target == nr_cpumask_bits)
return prev_cpu;
schedstat_inc(sd->ttwu_move_affine);
- schedstat_inc(p->se.statistics.nr_wakeups_affine);
+ schedstat_inc(p->stats.nr_wakeups_affine);
return target;
}
@@ -7533,7 +7583,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
if (!cpumask_test_cpu(env->dst_cpu, p->cpus_ptr)) {
int cpu;
- schedstat_inc(p->se.statistics.nr_failed_migrations_affine);
+ schedstat_inc(p->stats.nr_failed_migrations_affine);
env->flags |= LBF_SOME_PINNED;
@@ -7564,7 +7614,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
env->flags &= ~LBF_ALL_PINNED;
if (task_running(env->src_rq, p)) {
- schedstat_inc(p->se.statistics.nr_failed_migrations_running);
+ schedstat_inc(p->stats.nr_failed_migrations_running);
return 0;
}
@@ -7582,12 +7632,12 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
if (tsk_cache_hot == 1) {
schedstat_inc(env->sd->lb_hot_gained[env->idle]);
- schedstat_inc(p->se.statistics.nr_forced_migrations);
+ schedstat_inc(p->stats.nr_forced_migrations);
}
return 1;
}
- schedstat_inc(p->se.statistics.nr_failed_migrations_hot);
+ schedstat_inc(p->stats.nr_failed_migrations_hot);
return 0;
}
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index af772ac0f32d..2d543a270dfe 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1008,8 +1008,8 @@ static void update_curr_rt(struct rq *rq)
if (unlikely((s64)delta_exec <= 0))
return;
- schedstat_set(curr->se.statistics.exec_max,
- max(curr->se.statistics.exec_max, delta_exec));
+ schedstat_set(curr->stats.exec_max,
+ max(curr->stats.exec_max, delta_exec));
curr->se.sum_exec_runtime += delta_exec;
account_group_exec_runtime(curr, delta_exec);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 871544bb9a38..b1cdb942c67d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -387,6 +387,9 @@ struct cfs_bandwidth {
struct task_group {
struct cgroup_subsys_state css;
+ /* schedstats of this group on each CPU */
+ struct sched_statistics **stats;
+
#ifdef CONFIG_FAIR_GROUP_SCHED
/* schedulable entities of this group on each CPU */
struct sched_entity **se;
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index c23b653ffc53..87242968712e 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -42,6 +42,42 @@ rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
#define schedstat_val(var) (var)
#define schedstat_val_or_zero(var) ((schedstat_enabled()) ? (var) : 0)
+static inline void free_tg_schedstats(struct task_group *tg)
+{
+ int i;
+
+ for_each_possible_cpu(i) {
+ if (tg->stats)
+ kfree(tg->stats[i]);
+ }
+
+ kfree(tg->stats);
+}
+
+static inline int alloc_tg_schedstats(struct task_group *tg)
+{
+ struct sched_statistics *stats;
+ int i;
+
+ /*
+ * This memory should be allocated whatever schedstat_enabled() or
+ * not.
+ */
+ tg->stats = kcalloc(nr_cpu_ids, sizeof(stats), GFP_KERNEL);
+ if (!tg->stats)
+ return 0;
+
+ for_each_possible_cpu(i) {
+ stats = kzalloc_node(sizeof(struct sched_statistics),
+ GFP_KERNEL, cpu_to_node(i));
+ if (!stats)
+ return 0;
+ tg->stats[i] = stats;
+ }
+
+ return 1;
+}
+
#else /* !CONFIG_SCHEDSTATS: */
static inline void rq_sched_info_arrive (struct rq *rq, unsigned long long delta) { }
static inline void rq_sched_info_dequeued(struct rq *rq, unsigned long long delta) { }
@@ -55,6 +91,16 @@ static inline void rq_sched_info_depart (struct rq *rq, unsigned long long delt
# define schedstat_set(var, val) do { } while (0)
# define schedstat_val(var) 0
# define schedstat_val_or_zero(var) 0
+
+static inline void free_tg_schedstats(struct task_group *tg)
+{
+}
+
+static inline int alloc_tg_schedstats(struct task_group *tg)
+{
+ return 1;
+}
+
#endif /* CONFIG_SCHEDSTATS */
#ifdef CONFIG_PSI
diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
index a5d289049388..f35cd67a0881 100644
--- a/kernel/sched/stop_task.c
+++ b/kernel/sched/stop_task.c
@@ -70,8 +70,8 @@ static void put_prev_task_stop(struct rq *rq, struct task_struct *prev)
if (unlikely((s64)delta_exec < 0))
delta_exec = 0;
- schedstat_set(curr->se.statistics.exec_max,
- max(curr->se.statistics.exec_max, delta_exec));
+ schedstat_set(curr->stats.exec_max,
+ max(curr->stats.exec_max, delta_exec));
curr->se.sum_exec_runtime += delta_exec;
account_group_exec_runtime(curr, delta_exec);
--
2.18.4
On Tue, Dec 01, 2020 at 07:54:13PM +0800, Yafang Shao wrote:
> If we want to use schedstats facility, we should move out of
> struct sched_statistics from the struct sched_entity or add it into other
> sctructs of sched entity as well. Obviously the latter one is bad because
> that requires more spaces. So we should move it into a common struct which
> can be used by all sched classes.
>
> The struct sched_statistics is the schedular statistics of a task_struct
> or a task_group. So we can move it into struct task_struct and
> struct task_group to achieve the goal.
>
> Below is the detailed explaination of the change in the structs.
>
> - Before this patch
>
> struct task_struct { |-> struct sched_entity {
> ... | ...
> struct sched_entity *se; ---| struct sched_statistics statistics;
> struct sched_rt_entity *rt; ...
> ... ...
> }; };
>
> struct task_group { |--> se[0]->statistics : schedstats of CPU0
> ... |
> #ifdef CONFIG_FAIR_GROUP_SCHED |
> struct sched_entity **se; --|--> se[1]->statistics : schedstats of CPU1
> |
> #endif |
> |--> se[N]->statistics : schedstats of CPUn
>
> #ifdef CONFIG_FAIR_GROUP_SCHED
> struct sched_rt_entity **rt_se; (N/A)
> #endif
> ...
> };
>
> The '**se' in task_group is allocated in the fair sched class, which is
> hard to be reused by other sched class.
>
> - After this patch
>
> struct task_struct {
> ...
> struct sched_statistics statistics;
> ...
> struct sched_entity *se;
> struct sched_rt_entity *rt;
> ...
> };
>
> struct task_group { |---> stats[0] : of CPU0
> ... |
> struct sched_statistics **stats; --|---> stats[1] : of CPU1
> ... |
> |---> stats[n] : of CPUn
> #ifdef CONFIG_FAIR_GROUP_SCHED
> struct sched_entity **se;
> #endif
> #ifdef CONFIG_RT_GROUP_SCHED
> struct sched_rt_entity **rt_se;
> #endif
> ...
> };
>
> After the patch it is clearly that both of se or rt_se can easily get the
> sched_statistics by a task_struct or a task_group.
>
> Signed-off-by: Yafang Shao <[email protected]>
I didn't see anything wrong as such, it's mostly a mechanical
conversion. The one slight caveat is the potential change in cache
location for the statistics but it's not necessarily negative. The stats
potentially move to a different cache line but it's less obvious whether
that even matters given the location is very similar.
There is increased overhead now when schedstats are *enabled* because
_schedstat_from_sched_entity() has to be called but it appears that it is
protected by a schedstat_enabled() check. So ok, schedstats when enabled
are now a bit more expensive but they were expensive in the first place
so does it matter?
I'd have been happied if there was a comparison with schedstats enabled
just in case the overhead is too high but it could also do with a second
set of eyeballs.
It's somewhat tentative but
Acked-by: Mel Gorman <[email protected]>
--
Mel Gorman
SUSE Labs
On Tue, Dec 1, 2020 at 8:41 PM Mel Gorman <[email protected]> wrote:
>
> On Tue, Dec 01, 2020 at 07:54:13PM +0800, Yafang Shao wrote:
> > If we want to use schedstats facility, we should move out of
> > struct sched_statistics from the struct sched_entity or add it into other
> > sctructs of sched entity as well. Obviously the latter one is bad because
> > that requires more spaces. So we should move it into a common struct which
> > can be used by all sched classes.
> >
> > The struct sched_statistics is the schedular statistics of a task_struct
> > or a task_group. So we can move it into struct task_struct and
> > struct task_group to achieve the goal.
> >
> > Below is the detailed explaination of the change in the structs.
> >
> > - Before this patch
> >
> > struct task_struct { |-> struct sched_entity {
> > ... | ...
> > struct sched_entity *se; ---| struct sched_statistics statistics;
> > struct sched_rt_entity *rt; ...
> > ... ...
> > }; };
> >
> > struct task_group { |--> se[0]->statistics : schedstats of CPU0
> > ... |
> > #ifdef CONFIG_FAIR_GROUP_SCHED |
> > struct sched_entity **se; --|--> se[1]->statistics : schedstats of CPU1
> > |
> > #endif |
> > |--> se[N]->statistics : schedstats of CPUn
> >
> > #ifdef CONFIG_FAIR_GROUP_SCHED
> > struct sched_rt_entity **rt_se; (N/A)
> > #endif
> > ...
> > };
> >
> > The '**se' in task_group is allocated in the fair sched class, which is
> > hard to be reused by other sched class.
> >
> > - After this patch
> >
> > struct task_struct {
> > ...
> > struct sched_statistics statistics;
> > ...
> > struct sched_entity *se;
> > struct sched_rt_entity *rt;
> > ...
> > };
> >
> > struct task_group { |---> stats[0] : of CPU0
> > ... |
> > struct sched_statistics **stats; --|---> stats[1] : of CPU1
> > ... |
> > |---> stats[n] : of CPUn
> > #ifdef CONFIG_FAIR_GROUP_SCHED
> > struct sched_entity **se;
> > #endif
> > #ifdef CONFIG_RT_GROUP_SCHED
> > struct sched_rt_entity **rt_se;
> > #endif
> > ...
> > };
> >
> > After the patch it is clearly that both of se or rt_se can easily get the
> > sched_statistics by a task_struct or a task_group.
> >
> > Signed-off-by: Yafang Shao <[email protected]>
>
> I didn't see anything wrong as such, it's mostly a mechanical
> conversion. The one slight caveat is the potential change in cache
> location for the statistics but it's not necessarily negative. The stats
> potentially move to a different cache line but it's less obvious whether
> that even matters given the location is very similar.
>
> There is increased overhead now when schedstats are *enabled* because
> _schedstat_from_sched_entity() has to be called but it appears that it is
> protected by a schedstat_enabled() check. So ok, schedstats when enabled
> are now a bit more expensive but they were expensive in the first place
> so does it matter?
>
> I'd have been happied if there was a comparison with schedstats enabled
> just in case the overhead is too high but it could also do with a second
> set of eyeballs.
>
Sure, I will do the comparison. Thanks for the review again.
> It's somewhat tentative but
>
> Acked-by: Mel Gorman <[email protected]>
>
> --
> Mel Gorman
> SUSE Labs
--
Thanks
Yafang