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-rw-r--r--kernel/irq/manage.c6
-rw-r--r--kernel/locking/locktorture.c10
-rw-r--r--kernel/rcu/rcuperf.c8
-rw-r--r--kernel/rcu/rcutorture.c7
-rw-r--r--kernel/sched/core.c50
-rw-r--r--kernel/sched/psi.c5
-rw-r--r--kernel/trace/ring_buffer_benchmark.c48
7 files changed, 77 insertions, 57 deletions
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 48c38e09c673..d55ba625d426 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1308,9 +1308,6 @@ static int
setup_irq_thread(struct irqaction *new, unsigned int irq, bool secondary)
{
struct task_struct *t;
- struct sched_param param = {
- .sched_priority = MAX_USER_RT_PRIO/2,
- };
if (!secondary) {
t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
@@ -1318,13 +1315,12 @@ setup_irq_thread(struct irqaction *new, unsigned int irq, bool secondary)
} else {
t = kthread_create(irq_thread, new, "irq/%d-s-%s", irq,
new->name);
- param.sched_priority -= 1;
}
if (IS_ERR(t))
return PTR_ERR(t);
- sched_setscheduler_nocheck(t, SCHED_FIFO, &param);
+ sched_set_fifo(t);
/*
* We keep the reference to the task struct even if
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 8ff6f50e06a0..9cfa5e89cff7 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -436,8 +436,6 @@ static int torture_rtmutex_lock(void) __acquires(torture_rtmutex)
static void torture_rtmutex_boost(struct torture_random_state *trsp)
{
- int policy;
- struct sched_param param;
const unsigned int factor = 50000; /* yes, quite arbitrary */
if (!rt_task(current)) {
@@ -448,8 +446,7 @@ static void torture_rtmutex_boost(struct torture_random_state *trsp)
*/
if (trsp && !(torture_random(trsp) %
(cxt.nrealwriters_stress * factor))) {
- policy = SCHED_FIFO;
- param.sched_priority = MAX_RT_PRIO - 1;
+ sched_set_fifo(current);
} else /* common case, do nothing */
return;
} else {
@@ -462,13 +459,10 @@ static void torture_rtmutex_boost(struct torture_random_state *trsp)
*/
if (!trsp || !(torture_random(trsp) %
(cxt.nrealwriters_stress * factor * 2))) {
- policy = SCHED_NORMAL;
- param.sched_priority = 0;
+ sched_set_normal(current, 0);
} else /* common case, do nothing */
return;
}
-
- sched_setscheduler_nocheck(current, policy, &param);
}
static void torture_rtmutex_delay(struct torture_random_state *trsp)
diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index ec903d781778..21448d3374e2 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -361,7 +361,6 @@ rcu_perf_writer(void *arg)
int i_max;
long me = (long)arg;
struct rcu_head *rhp = NULL;
- struct sched_param sp;
bool started = false, done = false, alldone = false;
u64 t;
u64 *wdp;
@@ -370,8 +369,7 @@ rcu_perf_writer(void *arg)
VERBOSE_PERFOUT_STRING("rcu_perf_writer task started");
WARN_ON(!wdpp);
set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
- sp.sched_priority = 1;
- sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
+ sched_set_fifo_low(current);
if (holdoff)
schedule_timeout_uninterruptible(holdoff * HZ);
@@ -427,9 +425,7 @@ retry:
started = true;
if (!done && i >= MIN_MEAS) {
done = true;
- sp.sched_priority = 0;
- sched_setscheduler_nocheck(current,
- SCHED_NORMAL, &sp);
+ sched_set_normal(current, 0);
pr_alert("%s%s rcu_perf_writer %ld has %d measurements\n",
perf_type, PERF_FLAG, me, MIN_MEAS);
if (atomic_inc_return(&n_rcu_perf_writer_finished) >=
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index d0d265304d14..f453bf8d2f1e 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -895,16 +895,11 @@ static int rcu_torture_boost(void *arg)
unsigned long endtime;
unsigned long oldstarttime;
struct rcu_boost_inflight rbi = { .inflight = 0 };
- struct sched_param sp;
VERBOSE_TOROUT_STRING("rcu_torture_boost started");
/* Set real-time priority. */
- sp.sched_priority = 1;
- if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
- VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
- n_rcu_torture_boost_rterror++;
- }
+ sched_set_fifo_low(current);
init_rcu_head_on_stack(&rbi.rcu);
/* Each pass through the following loop does one boost-test cycle. */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4a0e7b449b88..84758f34cdb0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5496,6 +5496,8 @@ static int _sched_setscheduler(struct task_struct *p, int policy,
* @policy: new policy.
* @param: structure containing the new RT priority.
*
+ * Use sched_set_fifo(), read its comment.
+ *
* Return: 0 on success. An error code otherwise.
*
* NOTE that the task may be already dead.
@@ -5505,13 +5507,11 @@ int sched_setscheduler(struct task_struct *p, int policy,
{
return _sched_setscheduler(p, policy, param, true);
}
-EXPORT_SYMBOL_GPL(sched_setscheduler);
int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
{
return __sched_setscheduler(p, attr, true, true);
}
-EXPORT_SYMBOL_GPL(sched_setattr);
int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr)
{
@@ -5536,7 +5536,51 @@ int sched_setscheduler_nocheck(struct task_struct *p, int policy,
{
return _sched_setscheduler(p, policy, param, false);
}
-EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck);
+
+/*
+ * SCHED_FIFO is a broken scheduler model; that is, it is fundamentally
+ * incapable of resource management, which is the one thing an OS really should
+ * be doing.
+ *
+ * This is of course the reason it is limited to privileged users only.
+ *
+ * Worse still; it is fundamentally impossible to compose static priority
+ * workloads. You cannot take two correctly working static prio workloads
+ * and smash them together and still expect them to work.
+ *
+ * For this reason 'all' FIFO tasks the kernel creates are basically at:
+ *
+ * MAX_RT_PRIO / 2
+ *
+ * The administrator _MUST_ configure the system, the kernel simply doesn't
+ * know enough information to make a sensible choice.
+ */
+void sched_set_fifo(struct task_struct *p)
+{
+ struct sched_param sp = { .sched_priority = MAX_RT_PRIO / 2 };
+ WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0);
+}
+EXPORT_SYMBOL_GPL(sched_set_fifo);
+
+/*
+ * For when you don't much care about FIFO, but want to be above SCHED_NORMAL.
+ */
+void sched_set_fifo_low(struct task_struct *p)
+{
+ struct sched_param sp = { .sched_priority = 1 };
+ WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0);
+}
+EXPORT_SYMBOL_GPL(sched_set_fifo_low);
+
+void sched_set_normal(struct task_struct *p, int nice)
+{
+ struct sched_attr attr = {
+ .sched_policy = SCHED_NORMAL,
+ .sched_nice = nice,
+ };
+ WARN_ON_ONCE(sched_setattr_nocheck(p, &attr) != 0);
+}
+EXPORT_SYMBOL_GPL(sched_set_normal);
static int
do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index e53b711bd643..967732c0766c 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -616,11 +616,8 @@ out:
static int psi_poll_worker(void *data)
{
struct psi_group *group = (struct psi_group *)data;
- struct sched_param param = {
- .sched_priority = 1,
- };
- sched_setscheduler_nocheck(current, SCHED_FIFO, &param);
+ sched_set_fifo_low(current);
while (true) {
wait_event_interruptible(group->poll_wait,
diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
index 8df0aa810950..78e576575b79 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -45,8 +45,8 @@ MODULE_PARM_DESC(write_iteration, "# of writes between timestamp readings");
static int producer_nice = MAX_NICE;
static int consumer_nice = MAX_NICE;
-static int producer_fifo = -1;
-static int consumer_fifo = -1;
+static int producer_fifo;
+static int consumer_fifo;
module_param(producer_nice, int, 0644);
MODULE_PARM_DESC(producer_nice, "nice prio for producer");
@@ -55,10 +55,10 @@ module_param(consumer_nice, int, 0644);
MODULE_PARM_DESC(consumer_nice, "nice prio for consumer");
module_param(producer_fifo, int, 0644);
-MODULE_PARM_DESC(producer_fifo, "fifo prio for producer");
+MODULE_PARM_DESC(producer_fifo, "use fifo for producer: 0 - disabled, 1 - low prio, 2 - fifo");
module_param(consumer_fifo, int, 0644);
-MODULE_PARM_DESC(consumer_fifo, "fifo prio for consumer");
+MODULE_PARM_DESC(consumer_fifo, "use fifo for consumer: 0 - disabled, 1 - low prio, 2 - fifo");
static int read_events;
@@ -303,22 +303,22 @@ static void ring_buffer_producer(void)
trace_printk("ERROR!\n");
if (!disable_reader) {
- if (consumer_fifo < 0)
+ if (consumer_fifo)
+ trace_printk("Running Consumer at SCHED_FIFO %s\n",
+ consumer_fifo == 1 ? "low" : "high");
+ else
trace_printk("Running Consumer at nice: %d\n",
consumer_nice);
- else
- trace_printk("Running Consumer at SCHED_FIFO %d\n",
- consumer_fifo);
}
- if (producer_fifo < 0)
+ if (producer_fifo)
+ trace_printk("Running Producer at SCHED_FIFO %s\n",
+ producer_fifo == 1 ? "low" : "high");
+ else
trace_printk("Running Producer at nice: %d\n",
producer_nice);
- else
- trace_printk("Running Producer at SCHED_FIFO %d\n",
- producer_fifo);
/* Let the user know that the test is running at low priority */
- if (producer_fifo < 0 && consumer_fifo < 0 &&
+ if (!producer_fifo && !consumer_fifo &&
producer_nice == MAX_NICE && consumer_nice == MAX_NICE)
trace_printk("WARNING!!! This test is running at lowest priority.\n");
@@ -455,21 +455,19 @@ static int __init ring_buffer_benchmark_init(void)
* Run them as low-prio background tasks by default:
*/
if (!disable_reader) {
- if (consumer_fifo >= 0) {
- struct sched_param param = {
- .sched_priority = consumer_fifo
- };
- sched_setscheduler(consumer, SCHED_FIFO, &param);
- } else
+ if (consumer_fifo >= 2)
+ sched_set_fifo(consumer);
+ else if (consumer_fifo == 1)
+ sched_set_fifo_low(consumer);
+ else
set_user_nice(consumer, consumer_nice);
}
- if (producer_fifo >= 0) {
- struct sched_param param = {
- .sched_priority = producer_fifo
- };
- sched_setscheduler(producer, SCHED_FIFO, &param);
- } else
+ if (producer_fifo >= 2)
+ sched_set_fifo(producer);
+ else if (producer_fifo == 1)
+ sched_set_fifo_low(producer);
+ else
set_user_nice(producer, producer_nice);
return 0;
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-02 20:20:41 +0000