From 29c00b4a1d9e277786120032aa8364631820d863 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 17 Jun 2011 15:53:19 -0700 Subject: rcu: Add event-tracing for RCU callback invocation There was recently some controversy about the overhead of invoking RCU callbacks. Add TRACE_EVENT()s to obtain fine-grained timings for the start and stop of a batch of callbacks and also for each callback invoked. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- kernel/rcu.h | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 79 insertions(+) create mode 100644 kernel/rcu.h (limited to 'kernel/rcu.h') diff --git a/kernel/rcu.h b/kernel/rcu.h new file mode 100644 index 00000000000..7bc16436aba --- /dev/null +++ b/kernel/rcu.h @@ -0,0 +1,79 @@ +/* + * Read-Copy Update definitions shared among RCU implementations. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright IBM Corporation, 2011 + * + * Author: Paul E. McKenney + */ + +#ifndef __LINUX_RCU_H +#define __LINUX_RCU_H + +/* + * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally + * by call_rcu() and rcu callback execution, and are therefore not part of the + * RCU API. Leaving in rcupdate.h because they are used by all RCU flavors. + */ + +#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD +# define STATE_RCU_HEAD_READY 0 +# define STATE_RCU_HEAD_QUEUED 1 + +extern struct debug_obj_descr rcuhead_debug_descr; + +static inline void debug_rcu_head_queue(struct rcu_head *head) +{ + WARN_ON_ONCE((unsigned long)head & 0x3); + debug_object_activate(head, &rcuhead_debug_descr); + debug_object_active_state(head, &rcuhead_debug_descr, + STATE_RCU_HEAD_READY, + STATE_RCU_HEAD_QUEUED); +} + +static inline void debug_rcu_head_unqueue(struct rcu_head *head) +{ + debug_object_active_state(head, &rcuhead_debug_descr, + STATE_RCU_HEAD_QUEUED, + STATE_RCU_HEAD_READY); + debug_object_deactivate(head, &rcuhead_debug_descr); +} +#else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ +static inline void debug_rcu_head_queue(struct rcu_head *head) +{ +} + +static inline void debug_rcu_head_unqueue(struct rcu_head *head) +{ +} +#endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ + +extern void kfree(const void *); + +static inline void __rcu_reclaim(struct rcu_head *head) +{ + unsigned long offset = (unsigned long)head->func; + + if (__is_kfree_rcu_offset(offset)) { + trace_rcu_invoke_kfree_callback(head, offset); + kfree((void *)head - offset); + } else { + trace_rcu_invoke_callback(head); + head->func(head); + } +} + +#endif /* __LINUX_RCU_H */ -- cgit v1.2.3-18-g5258