From e260be673a15b6125068270e0216a3bfbfc12f87 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 25 Jan 2008 21:08:24 +0100 Subject: 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 Signed-off-by: Dipankar Sarma Signed-off-by: Paul E. McKenney Reviewed-by: Steven Rostedt Signed-off-by: Ingo Molnar --- include/linux/rcupreempt_trace.h | 99 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 include/linux/rcupreempt_trace.h (limited to 'include/linux/rcupreempt_trace.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 + * + * Based on the original work by Paul McKenney + * 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 +#include + +#include + +/* + * 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 */ -- cgit v1.2.1