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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2008-01-25 21:08:24 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-01-25 21:08:24 +0100 |
commit | e260be673a15b6125068270e0216a3bfbfc12f87 (patch) | |
tree | f50760606d395bf6faa9e865f814761a3c88d32c /include | |
parent | e0ecfa7917cafe72f4a75f87e8bb5d8d51dc534f (diff) | |
download | linux-e260be673a15b6125068270e0216a3bfbfc12f87.tar.gz linux-e260be673a15b6125068270e0216a3bfbfc12f87.tar.bz2 linux-e260be673a15b6125068270e0216a3bfbfc12f87.zip |
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.h | 3 | ||||
-rw-r--r-- | include/linux/rcupdate.h | 11 | ||||
-rw-r--r-- | include/linux/rcupreempt.h | 86 | ||||
-rw-r--r-- | include/linux/rcupreempt_trace.h | 99 | ||||
-rw-r--r-- | include/linux/sched.h | 5 |
5 files changed, 200 insertions, 4 deletions
diff --git a/include/linux/rcuclassic.h b/include/linux/rcuclassic.h index 2b8b045a51d5..4d6624260b4c 100644 --- a/include/linux/rcuclassic.h +++ b/include/linux/rcuclassic.h @@ -157,5 +157,8 @@ extern void __rcu_init(void); extern void rcu_check_callbacks(int cpu, int user); extern void rcu_restart_cpu(int cpu); +extern long rcu_batches_completed(void); +extern long rcu_batches_completed_bh(void); + #endif /* __KERNEL__ */ #endif /* __LINUX_RCUCLASSIC_H */ diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 12aa13e13150..d32c14de270e 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -53,7 +53,11 @@ struct rcu_head { void (*func)(struct rcu_head *head); }; +#ifdef CONFIG_CLASSIC_RCU #include <linux/rcuclassic.h> +#else /* #ifdef CONFIG_CLASSIC_RCU */ +#include <linux/rcupreempt.h> +#endif /* #else #ifdef CONFIG_CLASSIC_RCU */ #define RCU_HEAD_INIT { .next = NULL, .func = NULL } #define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT @@ -231,13 +235,12 @@ extern void call_rcu_bh(struct rcu_head *head, /* Exported common interfaces */ extern void synchronize_rcu(void); extern void rcu_barrier(void); +extern long rcu_batches_completed(void); +extern long rcu_batches_completed_bh(void); /* Internal to kernel */ extern void rcu_init(void); -extern void rcu_check_callbacks(int cpu, int user); - -extern long rcu_batches_completed(void); -extern long rcu_batches_completed_bh(void); +extern int rcu_needs_cpu(int cpu); #endif /* __KERNEL__ */ #endif /* __LINUX_RCUPDATE_H */ 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 @@ +/* + * Read-Copy Update mechanism for mutual exclusion (RT implementation) + * + * 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 (C) IBM Corporation, 2006 + * + * Author: Paul McKenney <paulmck@us.ibm.com> + * + * Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com> + * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. + * Papers: + * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf + * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) + * + * For detailed explanation of Read-Copy Update mechanism see - + * Documentation/RCU + * + */ + +#ifndef __LINUX_RCUPREEMPT_H +#define __LINUX_RCUPREEMPT_H + +#ifdef __KERNEL__ + +#include <linux/cache.h> +#include <linux/spinlock.h> +#include <linux/threads.h> +#include <linux/percpu.h> +#include <linux/cpumask.h> +#include <linux/seqlock.h> + +#define rcu_qsctr_inc(cpu) +#define rcu_bh_qsctr_inc(cpu) +#define call_rcu_bh(head, rcu) call_rcu(head, rcu) + +extern void __rcu_read_lock(void); +extern void __rcu_read_unlock(void); +extern int rcu_pending(int cpu); +extern int rcu_needs_cpu(int cpu); + +#define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); } +#define __rcu_read_unlock_bh() { local_bh_enable(); rcu_read_unlock(); } + +extern void __synchronize_sched(void); + +extern void __rcu_init(void); +extern void rcu_check_callbacks(int cpu, int user); +extern void rcu_restart_cpu(int cpu); +extern long rcu_batches_completed(void); + +/* + * Return the number of RCU batches processed thus far. Useful for debug + * and statistic. The _bh variant is identifcal to straight RCU + */ +static inline long rcu_batches_completed_bh(void) +{ + return rcu_batches_completed(); +} + +#ifdef CONFIG_RCU_TRACE +struct rcupreempt_trace; +extern long *rcupreempt_flipctr(int cpu); +extern long rcupreempt_data_completed(void); +extern int rcupreempt_flip_flag(int cpu); +extern int rcupreempt_mb_flag(int cpu); +extern char *rcupreempt_try_flip_state_name(void); +extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu); +#endif + +struct softirq_action; + +#endif /* __KERNEL__ */ +#endif /* __LINUX_RCUPREEMPT_H */ diff --git a/include/linux/rcupreempt_trace.h b/include/linux/rcupreempt_trace.h new file mode 100644 index 000000000000..21cd6b2a5c42 --- /dev/null +++ b/include/linux/rcupreempt_trace.h @@ -0,0 +1,99 @@ +/* + * Read-Copy Update mechanism for mutual exclusion (RT implementation) + * + * 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 (C) IBM Corporation, 2006 + * + * Author: Paul McKenney <paulmck@us.ibm.com> + * + * Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com> + * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. + * Papers: + * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf + * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) + * + * For detailed explanation of the Preemptible Read-Copy Update mechanism see - + * http://lwn.net/Articles/253651/ + */ + +#ifndef __LINUX_RCUPREEMPT_TRACE_H +#define __LINUX_RCUPREEMPT_TRACE_H + +#ifdef __KERNEL__ +#include <linux/types.h> +#include <linux/kernel.h> + +#include <asm/atomic.h> + +/* + * PREEMPT_RCU data structures. + */ + +struct rcupreempt_trace { + long next_length; + long next_add; + long wait_length; + long wait_add; + long done_length; + long done_add; + long done_remove; + atomic_t done_invoked; + long rcu_check_callbacks; + atomic_t rcu_try_flip_1; + atomic_t rcu_try_flip_e1; + long rcu_try_flip_i1; + long rcu_try_flip_ie1; + long rcu_try_flip_g1; + long rcu_try_flip_a1; + long rcu_try_flip_ae1; + long rcu_try_flip_a2; + long rcu_try_flip_z1; + long rcu_try_flip_ze1; + long rcu_try_flip_z2; + long rcu_try_flip_m1; + long rcu_try_flip_me1; + long rcu_try_flip_m2; +}; + +#ifdef CONFIG_RCU_TRACE +#define RCU_TRACE(fn, arg) fn(arg); +#else +#define RCU_TRACE(fn, arg) +#endif + +extern void rcupreempt_trace_move2done(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_move2wait(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_e1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_i1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_ie1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_g1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_a1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_ae1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_a2(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_z1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_ze1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_z2(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_m1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_me1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_m2(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_check_callbacks(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_done_remove(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_invoke(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_next_add(struct rcupreempt_trace *trace); + +#endif /* __KERNEL__ */ +#endif /* __LINUX_RCUPREEMPT_TRACE_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index f2044e707004..72e1b8ecfbe1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -974,6 +974,11 @@ struct task_struct { int nr_cpus_allowed; unsigned int time_slice; +#ifdef CONFIG_PREEMPT_RCU + int rcu_read_lock_nesting; + int rcu_flipctr_idx; +#endif /* #ifdef CONFIG_PREEMPT_RCU */ + #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) struct sched_info sched_info; #endif |