Commit d4bd54fb authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

nohz_full: Add full-system idle states and variables 



This commit adds control variables and states for full-system idle.
The system will progress through the states in numerical order when
the system is fully idle (other than the timekeeping CPU), and reset
down to the initial state if any non-timekeeping CPU goes non-idle.
The current state is kept in full_sysidle_state.

One flavor of RCU will be in charge of driving the state machine,
defined by rcu_sysidle_state.  This should be the busiest flavor of RCU.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent eb348b89

kernel/rcutree_plugin.h

+17 −0
Original line number Original line Diff line number Diff line
@@ -2377,6 +2377,23 @@ static void rcu_kick_nohz_cpu(int cpu) 




#ifdef CONFIG_NO_HZ_FULL_SYSIDLE

#ifdef CONFIG_NO_HZ_FULL_SYSIDLE





/*

 * Define RCU flavor that holds sysidle state.  This needs to be the

 * most active flavor of RCU.

 */

#ifdef CONFIG_PREEMPT_RCU

static struct rcu_state __maybe_unused *rcu_sysidle_state = &rcu_preempt_state;

#else /* #ifdef CONFIG_PREEMPT_RCU */

static struct rcu_state __maybe_unused *rcu_sysidle_state = &rcu_sched_state;

#endif /* #else #ifdef CONFIG_PREEMPT_RCU */



static int __maybe_unused full_sysidle_state; /* Current system-idle state. */

#define RCU_SYSIDLE_NOT		0	/* Some CPU is not idle. */

#define RCU_SYSIDLE_SHORT	1	/* All CPUs idle for brief period. */

#define RCU_SYSIDLE_LONG	2	/* All CPUs idle for long enough. */

#define RCU_SYSIDLE_FULL	3	/* All CPUs idle, ready for sysidle. */

#define RCU_SYSIDLE_FULL_NOTED	4	/* Actually entered sysidle state. */



/*

/*

 * Invoked to note exit from irq or task transition to idle.  Note that

 * Invoked to note exit from irq or task transition to idle.  Note that

 * usermode execution does -not- count as idle here!  After all, we want

 * usermode execution does -not- count as idle here!  After all, we want

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