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sched/rt: Remove default bandwidth control

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Now that fair_server exists, we no longer need RT bandwidth control
unless RT_GROUP_SCHED.

Enable fair_server with parameters equivalent to RT throttling.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: "Vineeth Pillai (Google)" <vineeth@bitbyteword.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/14d562db55df5c3c780d91940743acb166895ef7.1716811044.git.bristot@kernel.org
This commit is contained in:
Peter Zijlstra
2024-05-27 14:06:55 +02:00
parent c8a85394cf
commit 5f6bd380c7
5 changed files with 120 additions and 142 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
kernel/sched/core.c
View File

@@ -8266,8 +8266,6 @@ void __init sched_init(void)
#endif /* CONFIG_RT_GROUP_SCHED */
}
init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime());
#ifdef CONFIG_SMP
init_defrootdomain();
#endif
@@ -8322,8 +8320,13 @@ void __init sched_init(void)
init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
#endif /* CONFIG_FAIR_GROUP_SCHED */
rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
#ifdef CONFIG_RT_GROUP_SCHED
/*
* This is required for init cpu because rt.c:__enable_runtime()
* starts working after scheduler_running, which is not the case
* yet.
*/
rq->rt.rt_runtime = global_rt_runtime();
init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
#endif
#ifdef CONFIG_SMP

5
kernel/sched/deadline.c
View File

@@ -1554,6 +1554,7 @@ throttle:
if (dl_se == &rq->fair_server)
return;
#ifdef CONFIG_RT_GROUP_SCHED
/*
* Because -- for now -- we share the rt bandwidth, we need to
* account our runtime there too, otherwise actual rt tasks
@@ -1578,6 +1579,7 @@ throttle:
rt_rq->rt_time += delta_exec;
raw_spin_unlock(&rt_rq->rt_runtime_lock);
}
#endif
}
/*
@@ -1632,8 +1634,7 @@ void dl_server_start(struct sched_dl_entity *dl_se)
* this before getting generic.
*/
if (!dl_server(dl_se)) {
/* Disabled */
u64 runtime = 0;
u64 runtime = 50 * NSEC_PER_MSEC;
u64 period = 1000 * NSEC_PER_MSEC;
dl_server_apply_params(dl_se, runtime, period, 1);

3
kernel/sched/debug.c
View File

@@ -885,9 +885,12 @@ void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq)
SEQ_printf(m, " .%-30s: %Ld.%06ld\n", #x, SPLIT_NS(rt_rq->x))
PU(rt_nr_running);
#ifdef CONFIG_RT_GROUP_SCHED
P(rt_throttled);
PN(rt_time);
PN(rt_runtime);
#endif
#undef PN
#undef PU

242
kernel/sched/rt.c
View File

@@ -8,10 +8,6 @@ int sched_rr_timeslice = RR_TIMESLICE;
/* More than 4 hours if BW_SHIFT equals 20. */
static const u64 max_rt_runtime = MAX_BW;
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
struct rt_bandwidth def_rt_bandwidth;
/*
* period over which we measure -rt task CPU usage in us.
* default: 1s
@@ -66,6 +62,40 @@ static int __init sched_rt_sysctl_init(void)
late_initcall(sched_rt_sysctl_init);
#endif
void init_rt_rq(struct rt_rq *rt_rq)
{
struct rt_prio_array *array;
int i;
array = &rt_rq->active;
for (i = 0; i < MAX_RT_PRIO; i++) {
INIT_LIST_HEAD(array->queue + i);
__clear_bit(i, array->bitmap);
}
/* delimiter for bitsearch: */
__set_bit(MAX_RT_PRIO, array->bitmap);
#if defined CONFIG_SMP
rt_rq->highest_prio.curr = MAX_RT_PRIO-1;
rt_rq->highest_prio.next = MAX_RT_PRIO-1;
rt_rq->overloaded = 0;
plist_head_init(&rt_rq->pushable_tasks);
#endif /* CONFIG_SMP */
/* We start is dequeued state, because no RT tasks are queued */
rt_rq->rt_queued = 0;
#ifdef CONFIG_RT_GROUP_SCHED
rt_rq->rt_time = 0;
rt_rq->rt_throttled = 0;
rt_rq->rt_runtime = 0;
raw_spin_lock_init(&rt_rq->rt_runtime_lock);
#endif
}
#ifdef CONFIG_RT_GROUP_SCHED
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
{
struct rt_bandwidth *rt_b =
@@ -130,35 +160,6 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
do_start_rt_bandwidth(rt_b);
}
void init_rt_rq(struct rt_rq *rt_rq)
{
struct rt_prio_array *array;
int i;
array = &rt_rq->active;
for (i = 0; i < MAX_RT_PRIO; i++) {
INIT_LIST_HEAD(array->queue + i);
__clear_bit(i, array->bitmap);
}
/* delimiter for bit-search: */
__set_bit(MAX_RT_PRIO, array->bitmap);
#if defined CONFIG_SMP
rt_rq->highest_prio.curr = MAX_RT_PRIO-1;
rt_rq->highest_prio.next = MAX_RT_PRIO-1;
rt_rq->overloaded = 0;
plist_head_init(&rt_rq->pushable_tasks);
#endif /* CONFIG_SMP */
/* We start is dequeued state, because no RT tasks are queued */
rt_rq->rt_queued = 0;
rt_rq->rt_time = 0;
rt_rq->rt_throttled = 0;
rt_rq->rt_runtime = 0;
raw_spin_lock_init(&rt_rq->rt_runtime_lock);
}
#ifdef CONFIG_RT_GROUP_SCHED
static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
{
hrtimer_cancel(&rt_b->rt_period_timer);
@@ -195,7 +196,6 @@ void unregister_rt_sched_group(struct task_group *tg)
{
if (tg->rt_se)
destroy_rt_bandwidth(&tg->rt_bandwidth);
}
void free_rt_sched_group(struct task_group *tg)
@@ -253,8 +253,7 @@ int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
if (!tg->rt_se)
goto err;
init_rt_bandwidth(&tg->rt_bandwidth,
ktime_to_ns(def_rt_bandwidth.rt_period), 0);
init_rt_bandwidth(&tg->rt_bandwidth, ktime_to_ns(global_rt_period()), 0);
for_each_possible_cpu(i) {
rt_rq = kzalloc_node(sizeof(struct rt_rq),
@@ -604,70 +603,6 @@ static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
return &rt_rq->tg->rt_bandwidth;
}
#else /* !CONFIG_RT_GROUP_SCHED */
static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
{
return rt_rq->rt_runtime;
}
static inline u64 sched_rt_period(struct rt_rq *rt_rq)
{
return ktime_to_ns(def_rt_bandwidth.rt_period);
}
typedef struct rt_rq *rt_rq_iter_t;
#define for_each_rt_rq(rt_rq, iter, rq) \
for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
#define for_each_sched_rt_entity(rt_se) \
for (; rt_se; rt_se = NULL)
static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
{
return NULL;
}
static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
{
struct rq *rq = rq_of_rt_rq(rt_rq);
if (!rt_rq->rt_nr_running)
return;
enqueue_top_rt_rq(rt_rq);
resched_curr(rq);
}
static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
{
dequeue_top_rt_rq(rt_rq, rt_rq->rt_nr_running);
}
static inline int rt_rq_throttled(struct rt_rq *rt_rq)
{
return rt_rq->rt_throttled;
}
static inline const struct cpumask *sched_rt_period_mask(void)
{
return cpu_online_mask;
}
static inline
struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
{
return &cpu_rq(cpu)->rt;
}
static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
{
return &def_rt_bandwidth;
}
#endif /* CONFIG_RT_GROUP_SCHED */
bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
{
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
@@ -859,7 +794,7 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
const struct cpumask *span;
span = sched_rt_period_mask();
#ifdef CONFIG_RT_GROUP_SCHED
/*
* FIXME: isolated CPUs should really leave the root task group,
* whether they are isolcpus or were isolated via cpusets, lest
@@ -871,7 +806,7 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
*/
if (rt_b == &root_task_group.rt_bandwidth)
span = cpu_online_mask;
#endif
for_each_cpu(i, span) {
int enqueue = 0;
struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
@@ -938,18 +873,6 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
return idle;
}
static inline int rt_se_prio(struct sched_rt_entity *rt_se)
{
#ifdef CONFIG_RT_GROUP_SCHED
struct rt_rq *rt_rq = group_rt_rq(rt_se);
if (rt_rq)
return rt_rq->highest_prio.curr;
#endif
return rt_task_of(rt_se)->prio;
}
static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
{
u64 runtime = sched_rt_runtime(rt_rq);
@@ -993,6 +916,72 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
return 0;
}
#else /* !CONFIG_RT_GROUP_SCHED */
typedef struct rt_rq *rt_rq_iter_t;
#define for_each_rt_rq(rt_rq, iter, rq) \
for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
#define for_each_sched_rt_entity(rt_se) \
for (; rt_se; rt_se = NULL)
static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
{
return NULL;
}
static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
{
struct rq *rq = rq_of_rt_rq(rt_rq);
if (!rt_rq->rt_nr_running)
return;
enqueue_top_rt_rq(rt_rq);
resched_curr(rq);
}
static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
{
dequeue_top_rt_rq(rt_rq, rt_rq->rt_nr_running);
}
static inline int rt_rq_throttled(struct rt_rq *rt_rq)
{
return false;
}
static inline const struct cpumask *sched_rt_period_mask(void)
{
return cpu_online_mask;
}
static inline
struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
{
return &cpu_rq(cpu)->rt;
}
#ifdef CONFIG_SMP
static void __enable_runtime(struct rq *rq) { }
static void __disable_runtime(struct rq *rq) { }
#endif
#endif /* CONFIG_RT_GROUP_SCHED */
static inline int rt_se_prio(struct sched_rt_entity *rt_se)
{
#ifdef CONFIG_RT_GROUP_SCHED
struct rt_rq *rt_rq = group_rt_rq(rt_se);
if (rt_rq)
return rt_rq->highest_prio.curr;
#endif
return rt_task_of(rt_se)->prio;
}
/*
* Update the current task's runtime statistics. Skip current tasks that
* are not in our scheduling class.
@@ -1000,7 +989,6 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
static void update_curr_rt(struct rq *rq)
{
struct task_struct *curr = rq->curr;
struct sched_rt_entity *rt_se = &curr->rt;
s64 delta_exec;
if (curr->sched_class != &rt_sched_class)
@@ -1010,6 +998,9 @@ static void update_curr_rt(struct rq *rq)
if (unlikely(delta_exec <= 0))
return;
#ifdef CONFIG_RT_GROUP_SCHED
struct sched_rt_entity *rt_se = &curr->rt;
if (!rt_bandwidth_enabled())
return;
@@ -1028,6 +1019,7 @@ static void update_curr_rt(struct rq *rq)
do_start_rt_bandwidth(sched_rt_bandwidth(rt_rq));
}
}
#endif
}
static void
@@ -1184,7 +1176,6 @@ dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
static void
inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
start_rt_bandwidth(&def_rt_bandwidth);
}
static inline
@@ -2912,19 +2903,6 @@ int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
#ifdef CONFIG_SYSCTL
static int sched_rt_global_constraints(void)
{
unsigned long flags;
int i;
raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
for_each_possible_cpu(i) {
struct rt_rq *rt_rq = &cpu_rq(i)->rt;
raw_spin_lock(&rt_rq->rt_runtime_lock);
rt_rq->rt_runtime = global_rt_runtime();
raw_spin_unlock(&rt_rq->rt_runtime_lock);
}
raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
return 0;
}
#endif /* CONFIG_SYSCTL */
@@ -2944,12 +2922,6 @@ static int sched_rt_global_validate(void)
static void sched_rt_do_global(void)
{
unsigned long flags;
raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
def_rt_bandwidth.rt_runtime = global_rt_runtime();
def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
}
static int sched_rt_handler(const struct ctl_table *table, int write, void *buffer,

3
kernel/sched/sched.h
View File

@@ -729,13 +729,13 @@ struct rt_rq {
#endif /* CONFIG_SMP */
int rt_queued;
#ifdef CONFIG_RT_GROUP_SCHED
int rt_throttled;
u64 rt_time;
u64 rt_runtime;
/* Nests inside the rq lock: */
raw_spinlock_t rt_runtime_lock;
#ifdef CONFIG_RT_GROUP_SCHED
unsigned int rt_nr_boosted;
struct rq *rq;
@@ -2519,7 +2519,6 @@ extern void reweight_task(struct task_struct *p, const struct load_weight *lw);
extern void resched_curr(struct rq *rq);
extern void resched_cpu(int cpu);
extern struct rt_bandwidth def_rt_bandwidth;
extern void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime);
extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq);