diff options
author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2008-01-25 15:08:24 -0500 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-01-25 15:08:24 -0500 |
commit | e260be673a15b6125068270e0216a3bfbfc12f87 (patch) | |
tree | f50760606d395bf6faa9e865f814761a3c88d32c /include/linux/rcupreempt.h | |
parent | e0ecfa7917cafe72f4a75f87e8bb5d8d51dc534f (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/linux/rcupreempt.h')
-rw-r--r-- | include/linux/rcupreempt.h | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h new file mode 100644 index 000000000000..ece8eb3e4151 --- /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 | |||
49 | extern void __rcu_read_lock(void); | ||
50 | extern void __rcu_read_unlock(void); | ||
51 | extern int rcu_pending(int cpu); | ||
52 | extern 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 | |||
57 | extern void __synchronize_sched(void); | ||
58 | |||
59 | extern void __rcu_init(void); | ||
60 | extern void rcu_check_callbacks(int cpu, int user); | ||
61 | extern void rcu_restart_cpu(int cpu); | ||
62 | extern 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 | */ | ||
68 | static inline long rcu_batches_completed_bh(void) | ||
69 | { | ||
70 | return rcu_batches_completed(); | ||
71 | } | ||
72 | |||
73 | #ifdef CONFIG_RCU_TRACE | ||
74 | struct rcupreempt_trace; | ||
75 | extern long *rcupreempt_flipctr(int cpu); | ||
76 | extern long rcupreempt_data_completed(void); | ||
77 | extern int rcupreempt_flip_flag(int cpu); | ||
78 | extern int rcupreempt_mb_flag(int cpu); | ||
79 | extern char *rcupreempt_try_flip_state_name(void); | ||
80 | extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu); | ||
81 | #endif | ||
82 | |||
83 | struct softirq_action; | ||
84 | |||
85 | #endif /* __KERNEL__ */ | ||
86 | #endif /* __LINUX_RCUPREEMPT_H */ | ||