rcu: Remove nohz_full full-system-idle state machine
The NO_HZ_FULL_SYSIDLE full-system-idle capability was added in 2013
by commit 0edd1b1784cb ("nohz_full: Add full-system-idle state machine"),
but has not been used. This commit therefore removes it.
If it turns out to be needed later, this commit can always be reverted.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 187ac3f..51d4c3a 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -270,10 +270,6 @@ void rcu_bh_qs(void)
static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
.dynticks_nesting = DYNTICK_TASK_EXIT_IDLE,
.dynticks = ATOMIC_INIT(RCU_DYNTICK_CTRL_CTR),
-#ifdef CONFIG_NO_HZ_FULL_SYSIDLE
- .dynticks_idle_nesting = DYNTICK_TASK_NEST_VALUE,
- .dynticks_idle = ATOMIC_INIT(1),
-#endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
};
/*
@@ -546,10 +542,7 @@ module_param(jiffies_till_sched_qs, ulong, 0644);
static bool rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp,
struct rcu_data *rdp);
-static void force_qs_rnp(struct rcu_state *rsp,
- int (*f)(struct rcu_data *rsp, bool *isidle,
- unsigned long *maxj),
- bool *isidle, unsigned long *maxj);
+static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *rsp));
static void force_quiescent_state(struct rcu_state *rsp);
static int rcu_pending(void);
@@ -854,7 +847,6 @@ void rcu_idle_enter(void)
local_irq_save(flags);
rcu_eqs_enter(false);
- rcu_sysidle_enter(0);
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(rcu_idle_enter);
@@ -904,7 +896,6 @@ void rcu_irq_exit(void)
trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nesting, rdtp->dynticks_nesting - 1);
rdtp->dynticks_nesting--;
}
- rcu_sysidle_enter(1);
}
/*
@@ -986,7 +977,6 @@ void rcu_idle_exit(void)
local_irq_save(flags);
rcu_eqs_exit(false);
- rcu_sysidle_exit(0);
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(rcu_idle_exit);
@@ -1038,7 +1028,6 @@ void rcu_irq_enter(void)
trace_rcu_dyntick(TPS("++="), oldval, rdtp->dynticks_nesting);
else
rcu_eqs_exit_common(oldval, true);
- rcu_sysidle_exit(1);
}
/*
@@ -1217,11 +1206,9 @@ static int rcu_is_cpu_rrupt_from_idle(void)
* credit them with an implicit quiescent state. Return 1 if this CPU
* is in dynticks idle mode, which is an extended quiescent state.
*/
-static int dyntick_save_progress_counter(struct rcu_data *rdp,
- bool *isidle, unsigned long *maxj)
+static int dyntick_save_progress_counter(struct rcu_data *rdp)
{
rdp->dynticks_snap = rcu_dynticks_snap(rdp->dynticks);
- rcu_sysidle_check_cpu(rdp, isidle, maxj);
if (rcu_dynticks_in_eqs(rdp->dynticks_snap)) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
if (ULONG_CMP_LT(READ_ONCE(rdp->gpnum) + ULONG_MAX / 4,
@@ -1238,8 +1225,7 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp,
* idle state since the last call to dyntick_save_progress_counter()
* for this same CPU, or by virtue of having been offline.
*/
-static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
- bool *isidle, unsigned long *maxj)
+static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
{
unsigned long jtsq;
bool *rnhqp;
@@ -2105,25 +2091,16 @@ static bool rcu_gp_fqs_check_wake(struct rcu_state *rsp, int *gfp)
*/
static void rcu_gp_fqs(struct rcu_state *rsp, bool first_time)
{
- bool isidle = false;
- unsigned long maxj;
struct rcu_node *rnp = rcu_get_root(rsp);
WRITE_ONCE(rsp->gp_activity, jiffies);
rsp->n_force_qs++;
if (first_time) {
/* Collect dyntick-idle snapshots. */
- if (is_sysidle_rcu_state(rsp)) {
- isidle = true;
- maxj = jiffies - ULONG_MAX / 4;
- }
- force_qs_rnp(rsp, dyntick_save_progress_counter,
- &isidle, &maxj);
- rcu_sysidle_report_gp(rsp, isidle, maxj);
+ force_qs_rnp(rsp, dyntick_save_progress_counter);
} else {
/* Handle dyntick-idle and offline CPUs. */
- isidle = true;
- force_qs_rnp(rsp, rcu_implicit_dynticks_qs, &isidle, &maxj);
+ force_qs_rnp(rsp, rcu_implicit_dynticks_qs);
}
/* Clear flag to prevent immediate re-entry. */
if (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
@@ -2895,10 +2872,7 @@ void rcu_check_callbacks(int user)
*
* The caller must have suppressed start of new grace periods.
*/
-static void force_qs_rnp(struct rcu_state *rsp,
- int (*f)(struct rcu_data *rsp, bool *isidle,
- unsigned long *maxj),
- bool *isidle, unsigned long *maxj)
+static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *rsp))
{
int cpu;
unsigned long flags;
@@ -2937,7 +2911,7 @@ static void force_qs_rnp(struct rcu_state *rsp,
for_each_leaf_node_possible_cpu(rnp, cpu) {
unsigned long bit = leaf_node_cpu_bit(rnp, cpu);
if ((rnp->qsmask & bit) != 0) {
- if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj))
+ if (f(per_cpu_ptr(rsp->rda, cpu)))
mask |= bit;
}
}
@@ -3793,7 +3767,6 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
!init_nocb_callback_list(rdp))
rcu_segcblist_init(&rdp->cblist); /* Re-enable callbacks. */
rdp->dynticks->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
- rcu_sysidle_init_percpu_data(rdp->dynticks);
rcu_dynticks_eqs_online();
raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */