Kernel/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2025-01-17 18:56:24 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

sched/rt: Try to restart rt period timer when rt runtime exceeded

Browse Source 
[ Upstream commit 9b58e976b3b391c0cf02e038d53dd0478ed3013c ]

When rt_runtime is modified from -1 to a valid control value, it may
cause the task to be throttled all the time. Operations like the following
will trigger the bug. E.g:

  1. echo -1 > /proc/sys/kernel/sched_rt_runtime_us
  2. Run a FIFO task named A that executes while(1)
  3. echo 950000 > /proc/sys/kernel/sched_rt_runtime_us

When rt_runtime is -1, The rt period timer will not be activated when task
A enqueued. And then the task will be throttled after setting rt_runtime to
950,000. The task will always be throttled because the rt period timer is
not activated.

Fixes: d0b27fa77854 ("sched: rt-group: synchonised bandwidth period")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Li Hua <hucool.lihua@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211203033618.11895-1-hucool.lihua@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Li Hua 2021-12-03 03:36:18 +00:00 committed by Greg Kroah-Hartman
parent 183f76ddc1
commit e6bc7279b1
1 changed files with 18 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
kernel/sched/rt.c
View File

@ -50,11 +50,8 @@ void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
rt_b->rt_period_timer.function = sched_rt_period_timer;
}
static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
static inline void do_start_rt_bandwidth(struct rt_bandwidth *rt_b)
{
if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
return;
raw_spin_lock(&rt_b->rt_runtime_lock);
if (!rt_b->rt_period_active) {
rt_b->rt_period_active = 1;
@ -72,6 +69,14 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
raw_spin_unlock(&rt_b->rt_runtime_lock);
}
static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
{
if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
return;
do_start_rt_bandwidth(rt_b);
}
void init_rt_rq(struct rt_rq *rt_rq)
{
struct rt_prio_array *array;
@ -980,13 +985,17 @@ static void update_curr_rt(struct rq *rq)
for_each_sched_rt_entity(rt_se) {
struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
int exceeded;
if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
raw_spin_lock(&rt_rq->rt_runtime_lock);
rt_rq->rt_time += delta_exec;
if (sched_rt_runtime_exceeded(rt_rq))
exceeded = sched_rt_runtime_exceeded(rt_rq);
if (exceeded)
resched_curr(rq);
raw_spin_unlock(&rt_rq->rt_runtime_lock);
if (exceeded)
do_start_rt_bandwidth(sched_rt_bandwidth(rt_rq));
}
}
}
@ -2655,8 +2664,12 @@ 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);
}
int sched_rt_handler(struct ctl_table *table, int write,