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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2008-01-25 15:08:24 -0500
committerIngo Molnar <mingo@elte.hu>2008-01-25 15:08:24 -0500
commite260be673a15b6125068270e0216a3bfbfc12f87 (patch)
treef50760606d395bf6faa9e865f814761a3c88d32c /include
parente0ecfa7917cafe72f4a75f87e8bb5d8d51dc534f (diff)
Preempt-RCU: implementation
This patch implements a new version of RCU which allows its read-side critical sections to be preempted. It uses a set of counter pairs to keep track of the read-side critical sections and flips them when all tasks exit read-side critical section. The details of this implementation can be found in this paper - http://www.rdrop.com/users/paulmck/RCU/OLSrtRCU.2006.08.11a.pdf and the article- http://lwn.net/Articles/253651/ This patch was developed as a part of the -rt kernel development and meant to provide better latencies when read-side critical sections of RCU don't disable preemption. As a consequence of keeping track of RCU readers, the readers have a slight overhead (optimizations in the paper). This implementation co-exists with the "classic" RCU implementations and can be switched to at compiler. Also includes RCU tracing summarized in debugfs. [ akpm@linux-foundation.org: build fixes on non-preempt architectures ] Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com> Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com> Reviewed-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include')
-rw-r--r--include/linux/rcuclassic.h3
-rw-r--r--include/linux/rcupdate.h11
-rw-r--r--include/linux/rcupreempt.h86
-rw-r--r--include/linux/rcupreempt_trace.h99
-rw-r--r--include/linux/sched.h5
5 files changed, 200 insertions, 4 deletions
diff --git a/include/linux/rcuclassic.h b/include/linux/rcuclassic.h
index 2b8b045a51..4d6624260b 100644
--- a/include/linux/rcuclassic.h
+++ b/include/linux/rcuclassic.h
@@ -157,5 +157,8 @@ extern void __rcu_init(void);
157extern void rcu_check_callbacks(int cpu, int user); 157extern void rcu_check_callbacks(int cpu, int user);
158extern void rcu_restart_cpu(int cpu); 158extern void rcu_restart_cpu(int cpu);
159 159
160extern long rcu_batches_completed(void);
161extern long rcu_batches_completed_bh(void);
162
160#endif /* __KERNEL__ */ 163#endif /* __KERNEL__ */
161#endif /* __LINUX_RCUCLASSIC_H */ 164#endif /* __LINUX_RCUCLASSIC_H */
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 12aa13e131..d32c14de27 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -53,7 +53,11 @@ struct rcu_head {
53 void (*func)(struct rcu_head *head); 53 void (*func)(struct rcu_head *head);
54}; 54};
55 55
56#ifdef CONFIG_CLASSIC_RCU
56#include <linux/rcuclassic.h> 57#include <linux/rcuclassic.h>
58#else /* #ifdef CONFIG_CLASSIC_RCU */
59#include <linux/rcupreempt.h>
60#endif /* #else #ifdef CONFIG_CLASSIC_RCU */
57 61
58#define RCU_HEAD_INIT { .next = NULL, .func = NULL } 62#define RCU_HEAD_INIT { .next = NULL, .func = NULL }
59#define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT 63#define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT
@@ -231,13 +235,12 @@ extern void call_rcu_bh(struct rcu_head *head,
231/* Exported common interfaces */ 235/* Exported common interfaces */
232extern void synchronize_rcu(void); 236extern void synchronize_rcu(void);
233extern void rcu_barrier(void); 237extern void rcu_barrier(void);
238extern long rcu_batches_completed(void);
239extern long rcu_batches_completed_bh(void);
234 240
235/* Internal to kernel */ 241/* Internal to kernel */
236extern void rcu_init(void); 242extern void rcu_init(void);
237extern void rcu_check_callbacks(int cpu, int user); 243extern int rcu_needs_cpu(int cpu);
238
239extern long rcu_batches_completed(void);
240extern long rcu_batches_completed_bh(void);
241 244
242#endif /* __KERNEL__ */ 245#endif /* __KERNEL__ */
243#endif /* __LINUX_RCUPDATE_H */ 246#endif /* __LINUX_RCUPDATE_H */
diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h
new file mode 100644
index 0000000000..ece8eb3e41
--- /dev/null
+++ b/include/linux/rcupreempt.h
@@ -0,0 +1,86 @@
1/*
2 * Read-Copy Update mechanism for mutual exclusion (RT implementation)
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright (C) IBM Corporation, 2006
19 *
20 * Author: Paul McKenney <paulmck@us.ibm.com>
21 *
22 * Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com>
23 * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
24 * Papers:
25 * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
26 * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
27 *
28 * For detailed explanation of Read-Copy Update mechanism see -
29 * Documentation/RCU
30 *
31 */
32
33#ifndef __LINUX_RCUPREEMPT_H
34#define __LINUX_RCUPREEMPT_H
35
36#ifdef __KERNEL__
37
38#include <linux/cache.h>
39#include <linux/spinlock.h>
40#include <linux/threads.h>
41#include <linux/percpu.h>
42#include <linux/cpumask.h>
43#include <linux/seqlock.h>
44
45#define rcu_qsctr_inc(cpu)
46#define rcu_bh_qsctr_inc(cpu)
47#define call_rcu_bh(head, rcu) call_rcu(head, rcu)
48
49extern void __rcu_read_lock(void);
50extern void __rcu_read_unlock(void);
51extern int rcu_pending(int cpu);
52extern int rcu_needs_cpu(int cpu);
53
54#define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); }
55#define __rcu_read_unlock_bh() { local_bh_enable(); rcu_read_unlock(); }
56
57extern void __synchronize_sched(void);
58
59extern void __rcu_init(void);
60extern void rcu_check_callbacks(int cpu, int user);
61extern void rcu_restart_cpu(int cpu);
62extern long rcu_batches_completed(void);
63
64/*
65 * Return the number of RCU batches processed thus far. Useful for debug
66 * and statistic. The _bh variant is identifcal to straight RCU
67 */
68static inline long rcu_batches_completed_bh(void)
69{
70 return rcu_batches_completed();
71}
72
73#ifdef CONFIG_RCU_TRACE
74struct rcupreempt_trace;
75extern long *rcupreempt_flipctr(int cpu);
76extern long rcupreempt_data_completed(void);
77extern int rcupreempt_flip_flag(int cpu);
78extern int rcupreempt_mb_flag(int cpu);
79extern char *rcupreempt_try_flip_state_name(void);
80extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu);
81#endif
82
83struct softirq_action;
84
85#endif /* __KERNEL__ */
86#endif /* __LINUX_RCUPREEMPT_H */
diff --git a/include/linux/rcupreempt_trace.h b/include/linux/rcupreempt_trace.h
new file mode 100644
index 0000000000..21cd6b2a5c
--- /dev/null
+++ b/include/linux/rcupreempt_trace.h
@@ -0,0 +1,99 @@
1/*
2 * Read-Copy Update mechanism for mutual exclusion (RT implementation)
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright (C) IBM Corporation, 2006
19 *
20 * Author: Paul McKenney <paulmck@us.ibm.com>
21 *
22 * Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com>
23 * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
24 * Papers:
25 * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
26 * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
27 *
28 * For detailed explanation of the Preemptible Read-Copy Update mechanism see -
29 * http://lwn.net/Articles/253651/
30 */
31
32#ifndef __LINUX_RCUPREEMPT_TRACE_H
33#define __LINUX_RCUPREEMPT_TRACE_H
34
35#ifdef __KERNEL__
36#include <linux/types.h>
37#include <linux/kernel.h>
38
39#include <asm/atomic.h>
40
41/*
42 * PREEMPT_RCU data structures.
43 */
44
45struct rcupreempt_trace {
46 long next_length;
47 long next_add;
48 long wait_length;
49 long wait_add;
50 long done_length;
51 long done_add;
52 long done_remove;
53 atomic_t done_invoked;
54 long rcu_check_callbacks;
55 atomic_t rcu_try_flip_1;
56 atomic_t rcu_try_flip_e1;
57 long rcu_try_flip_i1;
58 long rcu_try_flip_ie1;
59 long rcu_try_flip_g1;
60 long rcu_try_flip_a1;
61 long rcu_try_flip_ae1;
62 long rcu_try_flip_a2;
63 long rcu_try_flip_z1;
64 long rcu_try_flip_ze1;
65 long rcu_try_flip_z2;
66 long rcu_try_flip_m1;
67 long rcu_try_flip_me1;
68 long rcu_try_flip_m2;
69};
70
71#ifdef CONFIG_RCU_TRACE
72#define RCU_TRACE(fn, arg) fn(arg);
73#else
74#define RCU_TRACE(fn, arg)
75#endif
76
77extern void rcupreempt_trace_move2done(struct rcupreempt_trace *trace);
78extern void rcupreempt_trace_move2wait(struct rcupreempt_trace *trace);
79extern void rcupreempt_trace_try_flip_1(struct rcupreempt_trace *trace);
80extern void rcupreempt_trace_try_flip_e1(struct rcupreempt_trace *trace);
81extern void rcupreempt_trace_try_flip_i1(struct rcupreempt_trace *trace);
82extern void rcupreempt_trace_try_flip_ie1(struct rcupreempt_trace *trace);
83extern void rcupreempt_trace_try_flip_g1(struct rcupreempt_trace *trace);
84extern void rcupreempt_trace_try_flip_a1(struct rcupreempt_trace *trace);
85extern void rcupreempt_trace_try_flip_ae1(struct rcupreempt_trace *trace);
86extern void rcupreempt_trace_try_flip_a2(struct rcupreempt_trace *trace);
87extern void rcupreempt_trace_try_flip_z1(struct rcupreempt_trace *trace);
88extern void rcupreempt_trace_try_flip_ze1(struct rcupreempt_trace *trace);
89extern void rcupreempt_trace_try_flip_z2(struct rcupreempt_trace *trace);
90extern void rcupreempt_trace_try_flip_m1(struct rcupreempt_trace *trace);
91extern void rcupreempt_trace_try_flip_me1(struct rcupreempt_trace *trace);
92extern void rcupreempt_trace_try_flip_m2(struct rcupreempt_trace *trace);
93extern void rcupreempt_trace_check_callbacks(struct rcupreempt_trace *trace);
94extern void rcupreempt_trace_done_remove(struct rcupreempt_trace *trace);
95extern void rcupreempt_trace_invoke(struct rcupreempt_trace *trace);
96extern void rcupreempt_trace_next_add(struct rcupreempt_trace *trace);
97
98#endif /* __KERNEL__ */
99#endif /* __LINUX_RCUPREEMPT_TRACE_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f2044e7070..72e1b8ecfb 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -974,6 +974,11 @@ struct task_struct {
974 int nr_cpus_allowed; 974 int nr_cpus_allowed;
975 unsigned int time_slice; 975 unsigned int time_slice;
976 976
977#ifdef CONFIG_PREEMPT_RCU
978 int rcu_read_lock_nesting;
979 int rcu_flipctr_idx;
980#endif /* #ifdef CONFIG_PREEMPT_RCU */
981
977#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) 982#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
978 struct sched_info sched_info; 983 struct sched_info sched_info;
979#endif 984#endif
generated by cgit v1.2.2 (git 2.25.0) at 2026-02-24 22:21:23 -0500