486e259340
When CONFIG_RCU_FAST_NO_HZ is enabled, RCU will allow a given CPU to enter dyntick-idle mode even if it still has RCU callbacks queued. RCU avoids system hangs in this case by scheduling a timer for several jiffies in the future. However, if all of the callbacks on that CPU are from kfree_rcu(), there is no reason to wake the CPU up, as it is not a problem to defer freeing of memory. This commit therefore tracks the number of callbacks on a given CPU that are from kfree_rcu(), and avoids scheduling the timer if all of a given CPU's callbacks are from kfree_rcu(). Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
175 lines
3.6 KiB
C
175 lines
3.6 KiB
C
/*
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* Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright IBM Corporation, 2008
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*
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* Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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*
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* For detailed explanation of Read-Copy Update mechanism see -
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* Documentation/RCU
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*/
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#ifndef __LINUX_TINY_H
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#define __LINUX_TINY_H
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#include <linux/cache.h>
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#ifdef CONFIG_RCU_BOOST
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static inline void rcu_init(void)
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{
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}
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#else /* #ifdef CONFIG_RCU_BOOST */
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void rcu_init(void);
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#endif /* #else #ifdef CONFIG_RCU_BOOST */
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static inline void rcu_barrier_bh(void)
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{
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wait_rcu_gp(call_rcu_bh);
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}
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static inline void rcu_barrier_sched(void)
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{
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wait_rcu_gp(call_rcu_sched);
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}
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#ifdef CONFIG_TINY_RCU
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static inline void synchronize_rcu_expedited(void)
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{
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synchronize_sched(); /* Only one CPU, so pretty fast anyway!!! */
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}
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static inline void rcu_barrier(void)
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{
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rcu_barrier_sched(); /* Only one CPU, so only one list of callbacks! */
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}
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#else /* #ifdef CONFIG_TINY_RCU */
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void synchronize_rcu_expedited(void);
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static inline void rcu_barrier(void)
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{
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wait_rcu_gp(call_rcu);
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}
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#endif /* #else #ifdef CONFIG_TINY_RCU */
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static inline void synchronize_rcu_bh(void)
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{
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synchronize_sched();
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}
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static inline void synchronize_rcu_bh_expedited(void)
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{
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synchronize_sched();
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}
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static inline void synchronize_sched_expedited(void)
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{
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synchronize_sched();
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}
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static inline void kfree_call_rcu(struct rcu_head *head,
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void (*func)(struct rcu_head *rcu))
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{
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call_rcu(head, func);
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}
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#ifdef CONFIG_TINY_RCU
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static inline void rcu_preempt_note_context_switch(void)
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{
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}
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static inline void exit_rcu(void)
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{
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}
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static inline int rcu_needs_cpu(int cpu)
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{
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return 0;
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}
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#else /* #ifdef CONFIG_TINY_RCU */
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void rcu_preempt_note_context_switch(void);
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extern void exit_rcu(void);
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int rcu_preempt_needs_cpu(void);
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static inline int rcu_needs_cpu(int cpu)
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{
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return rcu_preempt_needs_cpu();
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}
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#endif /* #else #ifdef CONFIG_TINY_RCU */
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static inline void rcu_note_context_switch(int cpu)
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{
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rcu_sched_qs(cpu);
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rcu_preempt_note_context_switch();
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}
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/*
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* Take advantage of the fact that there is only one CPU, which
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* allows us to ignore virtualization-based context switches.
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*/
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static inline void rcu_virt_note_context_switch(int cpu)
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{
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}
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/*
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* Return the number of grace periods.
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*/
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static inline long rcu_batches_completed(void)
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{
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return 0;
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}
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/*
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* Return the number of bottom-half grace periods.
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*/
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static inline long rcu_batches_completed_bh(void)
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{
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return 0;
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}
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static inline void rcu_force_quiescent_state(void)
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{
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}
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static inline void rcu_bh_force_quiescent_state(void)
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{
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}
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static inline void rcu_sched_force_quiescent_state(void)
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{
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}
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static inline void rcu_cpu_stall_reset(void)
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{
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}
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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extern int rcu_scheduler_active __read_mostly;
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extern void rcu_scheduler_starting(void);
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#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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static inline void rcu_scheduler_starting(void)
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{
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}
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#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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#endif /* __LINUX_RCUTINY_H */
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