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Date: Sun, 12 Apr 2020 14:18:40 -0000
From: Thomas Gleixner <tglx@...utronix.de>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [GIT pull] sched/urgent for 5.7-rc1
Linus,
please pull the latest sched/urgent branch from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-2020-04-12
up to: 96e74ebf8d59: sched/debug: Add task uclamp values to SCHED_DEBUG procfs
Scheduler fixes/updates:
- Deduplicate the average computations in the scheduler core and the fair
class code.
- Fix a raise between runtime distribution and assignement which can cause
exceeding the quota by up to 70%.
- Prevent negative results in the imbalanace calculation
- Remove a stale warning in the workqueue code which can be triggered
since the call site was moved out of preempt disabled code. It's a false
positive.
- Deduplicate the print macros for procfs
- Add the ucmap values to the SCHED_DEBUG procfs output for completness
Thanks,
tglx
------------------>
Aubrey Li (1):
sched/fair: Fix negative imbalance in imbalance calculation
Huaixin Chang (1):
sched/fair: Fix race between runtime distribution and assignment
Sebastian Andrzej Siewior (1):
workqueue: Remove the warning in wq_worker_sleeping()
Valentin Schneider (4):
sched/fair: Align rq->avg_idle and rq->avg_scan_cost
sched/debug: Remove redundant macro define
sched/debug: Factor out printing formats into common macros
sched/debug: Add task uclamp values to SCHED_DEBUG procfs
Vincent Donnefort (1):
sched/core: Remove unused rq::last_load_update_tick
kernel/sched/core.c | 10 ++--------
kernel/sched/debug.c | 44 ++++++++++++++++++--------------------------
kernel/sched/fair.c | 46 +++++++++++++++++++++-------------------------
kernel/sched/sched.h | 7 ++++++-
kernel/workqueue.c | 6 ++++--
5 files changed, 51 insertions(+), 62 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a2694ba82874..3a61a3b8eaa9 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2119,12 +2119,6 @@ int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
return cpu;
}
-static void update_avg(u64 *avg, u64 sample)
-{
- s64 diff = sample - *avg;
- *avg += diff >> 3;
-}
-
void sched_set_stop_task(int cpu, struct task_struct *stop)
{
struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
@@ -4126,7 +4120,8 @@ static inline void sched_submit_work(struct task_struct *tsk)
* it wants to wake up a task to maintain concurrency.
* As this function is called inside the schedule() context,
* we disable preemption to avoid it calling schedule() again
- * in the possible wakeup of a kworker.
+ * in the possible wakeup of a kworker and because wq_worker_sleeping()
+ * requires it.
*/
if (tsk->flags & (PF_WQ_WORKER | PF_IO_WORKER)) {
preempt_disable();
@@ -6699,7 +6694,6 @@ void __init sched_init(void)
rq_attach_root(rq, &def_root_domain);
#ifdef CONFIG_NO_HZ_COMMON
- rq->last_load_update_tick = jiffies;
rq->last_blocked_load_update_tick = jiffies;
atomic_set(&rq->nohz_flags, 0);
#endif
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 8331bc04aea2..a562df57a86e 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -816,10 +816,12 @@ static int __init init_sched_debug_procfs(void)
__initcall(init_sched_debug_procfs);
-#define __P(F) SEQ_printf(m, "%-45s:%21Ld\n", #F, (long long)F)
-#define P(F) SEQ_printf(m, "%-45s:%21Ld\n", #F, (long long)p->F)
-#define __PN(F) SEQ_printf(m, "%-45s:%14Ld.%06ld\n", #F, SPLIT_NS((long long)F))
-#define PN(F) SEQ_printf(m, "%-45s:%14Ld.%06ld\n", #F, SPLIT_NS((long long)p->F))
+#define __PS(S, F) SEQ_printf(m, "%-45s:%21Ld\n", S, (long long)(F))
+#define __P(F) __PS(#F, F)
+#define P(F) __PS(#F, p->F)
+#define __PSN(S, F) SEQ_printf(m, "%-45s:%14Ld.%06ld\n", S, SPLIT_NS((long long)(F)))
+#define __PN(F) __PSN(#F, F)
+#define PN(F) __PSN(#F, p->F)
#ifdef CONFIG_NUMA_BALANCING
@@ -868,18 +870,9 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
SEQ_printf(m,
"---------------------------------------------------------"
"----------\n");
-#define __P(F) \
- SEQ_printf(m, "%-45s:%21Ld\n", #F, (long long)F)
-#define P(F) \
- SEQ_printf(m, "%-45s:%21Ld\n", #F, (long long)p->F)
-#define P_SCHEDSTAT(F) \
- SEQ_printf(m, "%-45s:%21Ld\n", #F, (long long)schedstat_val(p->F))
-#define __PN(F) \
- SEQ_printf(m, "%-45s:%14Ld.%06ld\n", #F, SPLIT_NS((long long)F))
-#define PN(F) \
- SEQ_printf(m, "%-45s:%14Ld.%06ld\n", #F, SPLIT_NS((long long)p->F))
-#define PN_SCHEDSTAT(F) \
- SEQ_printf(m, "%-45s:%14Ld.%06ld\n", #F, SPLIT_NS((long long)schedstat_val(p->F)))
+
+#define P_SCHEDSTAT(F) __PS(#F, schedstat_val(p->F))
+#define PN_SCHEDSTAT(F) __PSN(#F, schedstat_val(p->F))
PN(se.exec_start);
PN(se.vruntime);
@@ -939,10 +932,8 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
}
__P(nr_switches);
- SEQ_printf(m, "%-45s:%21Ld\n",
- "nr_voluntary_switches", (long long)p->nvcsw);
- SEQ_printf(m, "%-45s:%21Ld\n",
- "nr_involuntary_switches", (long long)p->nivcsw);
+ __PS("nr_voluntary_switches", p->nvcsw);
+ __PS("nr_involuntary_switches", p->nivcsw);
P(se.load.weight);
#ifdef CONFIG_SMP
@@ -955,6 +946,12 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
P(se.avg.last_update_time);
P(se.avg.util_est.ewma);
P(se.avg.util_est.enqueued);
+#endif
+#ifdef CONFIG_UCLAMP_TASK
+ __PS("uclamp.min", p->uclamp[UCLAMP_MIN].value);
+ __PS("uclamp.max", p->uclamp[UCLAMP_MAX].value);
+ __PS("effective uclamp.min", uclamp_eff_value(p, UCLAMP_MIN));
+ __PS("effective uclamp.max", uclamp_eff_value(p, UCLAMP_MAX));
#endif
P(policy);
P(prio);
@@ -963,11 +960,7 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
P(dl.deadline);
}
#undef PN_SCHEDSTAT
-#undef PN
-#undef __PN
#undef P_SCHEDSTAT
-#undef P
-#undef __P
{
unsigned int this_cpu = raw_smp_processor_id();
@@ -975,8 +968,7 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
t0 = cpu_clock(this_cpu);
t1 = cpu_clock(this_cpu);
- SEQ_printf(m, "%-45s:%21Ld\n",
- "clock-delta", (long long)(t1-t0));
+ __PS("clock-delta", t1-t0);
}
sched_show_numa(p, m);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1ea3dddafe69..02f323b85b6d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4836,11 +4836,10 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
resched_curr(rq);
}
-static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, u64 remaining)
+static void distribute_cfs_runtime(struct cfs_bandwidth *cfs_b)
{
struct cfs_rq *cfs_rq;
- u64 runtime;
- u64 starting_runtime = remaining;
+ u64 runtime, remaining = 1;
rcu_read_lock();
list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
@@ -4855,10 +4854,13 @@ static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, u64 remaining)
/* By the above check, this should never be true */
SCHED_WARN_ON(cfs_rq->runtime_remaining > 0);
+ raw_spin_lock(&cfs_b->lock);
runtime = -cfs_rq->runtime_remaining + 1;
- if (runtime > remaining)
- runtime = remaining;
- remaining -= runtime;
+ if (runtime > cfs_b->runtime)
+ runtime = cfs_b->runtime;
+ cfs_b->runtime -= runtime;
+ remaining = cfs_b->runtime;
+ raw_spin_unlock(&cfs_b->lock);
cfs_rq->runtime_remaining += runtime;
@@ -4873,8 +4875,6 @@ static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, u64 remaining)
break;
}
rcu_read_unlock();
-
- return starting_runtime - remaining;
}
/*
@@ -4885,7 +4885,6 @@ static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, u64 remaining)
*/
static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun, unsigned long flags)
{
- u64 runtime;
int throttled;
/* no need to continue the timer with no bandwidth constraint */
@@ -4914,24 +4913,17 @@ static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun, u
cfs_b->nr_throttled += overrun;
/*
- * This check is repeated as we are holding onto the new bandwidth while
- * we unthrottle. This can potentially race with an unthrottled group
- * trying to acquire new bandwidth from the global pool. This can result
- * in us over-using our runtime if it is all used during this loop, but
- * only by limited amounts in that extreme case.
+ * This check is repeated as we release cfs_b->lock while we unthrottle.
*/
while (throttled && cfs_b->runtime > 0 && !cfs_b->distribute_running) {
- runtime = cfs_b->runtime;
cfs_b->distribute_running = 1;
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
/* we can't nest cfs_b->lock while distributing bandwidth */
- runtime = distribute_cfs_runtime(cfs_b, runtime);
+ distribute_cfs_runtime(cfs_b);
raw_spin_lock_irqsave(&cfs_b->lock, flags);
cfs_b->distribute_running = 0;
throttled = !list_empty(&cfs_b->throttled_cfs_rq);
-
- lsub_positive(&cfs_b->runtime, runtime);
}
/*
@@ -5065,10 +5057,9 @@ static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
if (!runtime)
return;
- runtime = distribute_cfs_runtime(cfs_b, runtime);
+ distribute_cfs_runtime(cfs_b);
raw_spin_lock_irqsave(&cfs_b->lock, flags);
- lsub_positive(&cfs_b->runtime, runtime);
cfs_b->distribute_running = 0;
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
}
@@ -6080,8 +6071,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask);
struct sched_domain *this_sd;
u64 avg_cost, avg_idle;
- u64 time, cost;
- s64 delta;
+ u64 time;
int this = smp_processor_id();
int cpu, nr = INT_MAX;
@@ -6119,9 +6109,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
}
time = cpu_clock(this) - time;
- cost = this_sd->avg_scan_cost;
- delta = (s64)(time - cost) / 8;
- this_sd->avg_scan_cost += delta;
+ update_avg(&this_sd->avg_scan_cost, time);
return cpu;
}
@@ -9048,6 +9036,14 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
sds->avg_load = (sds->total_load * SCHED_CAPACITY_SCALE) /
sds->total_capacity;
+ /*
+ * If the local group is more loaded than the selected
+ * busiest group don't try to pull any tasks.
+ */
+ if (local->avg_load >= busiest->avg_load) {
+ env->imbalance = 0;
+ return;
+ }
}
/*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 0f616bf7bce3..db3a57675ccf 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -195,6 +195,12 @@ static inline int task_has_dl_policy(struct task_struct *p)
#define cap_scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT)
+static inline void update_avg(u64 *avg, u64 sample)
+{
+ s64 diff = sample - *avg;
+ *avg += diff / 8;
+}
+
/*
* !! For sched_setattr_nocheck() (kernel) only !!
*
@@ -882,7 +888,6 @@ struct rq {
#endif
#ifdef CONFIG_NO_HZ_COMMON
#ifdef CONFIG_SMP
- unsigned long last_load_update_tick;
unsigned long last_blocked_load_update_tick;
unsigned int has_blocked_load;
#endif /* CONFIG_SMP */
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 3816a18c251e..891ccad5f271 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -858,7 +858,8 @@ void wq_worker_running(struct task_struct *task)
* @task: task going to sleep
*
* This function is called from schedule() when a busy worker is
- * going to sleep.
+ * going to sleep. Preemption needs to be disabled to protect ->sleeping
+ * assignment.
*/
void wq_worker_sleeping(struct task_struct *task)
{
@@ -875,7 +876,8 @@ void wq_worker_sleeping(struct task_struct *task)
pool = worker->pool;
- if (WARN_ON_ONCE(worker->sleeping))
+ /* Return if preempted before wq_worker_running() was reached */
+ if (worker->sleeping)
return;
worker->sleeping = 1;
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