e260be673a
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>
100 lines
3.6 KiB
C
100 lines
3.6 KiB
C
/*
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* Read-Copy Update mechanism for mutual exclusion (RT implementation)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) IBM Corporation, 2006
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*
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* Author: Paul McKenney <paulmck@us.ibm.com>
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*
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* Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com>
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* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
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* Papers:
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* http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
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* http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
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*
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* For detailed explanation of the Preemptible Read-Copy Update mechanism see -
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* http://lwn.net/Articles/253651/
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*/
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#ifndef __LINUX_RCUPREEMPT_TRACE_H
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#define __LINUX_RCUPREEMPT_TRACE_H
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#ifdef __KERNEL__
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <asm/atomic.h>
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/*
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* PREEMPT_RCU data structures.
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*/
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struct rcupreempt_trace {
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long next_length;
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long next_add;
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long wait_length;
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long wait_add;
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long done_length;
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long done_add;
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long done_remove;
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atomic_t done_invoked;
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long rcu_check_callbacks;
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atomic_t rcu_try_flip_1;
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atomic_t rcu_try_flip_e1;
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long rcu_try_flip_i1;
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long rcu_try_flip_ie1;
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long rcu_try_flip_g1;
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long rcu_try_flip_a1;
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long rcu_try_flip_ae1;
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long rcu_try_flip_a2;
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long rcu_try_flip_z1;
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long rcu_try_flip_ze1;
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long rcu_try_flip_z2;
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long rcu_try_flip_m1;
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long rcu_try_flip_me1;
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long rcu_try_flip_m2;
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};
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#ifdef CONFIG_RCU_TRACE
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#define RCU_TRACE(fn, arg) fn(arg);
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#else
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#define RCU_TRACE(fn, arg)
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#endif
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extern void rcupreempt_trace_move2done(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_move2wait(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_1(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_e1(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_i1(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_ie1(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_g1(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_a1(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_ae1(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_a2(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_z1(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_ze1(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_z2(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_m1(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_me1(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_try_flip_m2(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_check_callbacks(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_done_remove(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_invoke(struct rcupreempt_trace *trace);
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extern void rcupreempt_trace_next_add(struct rcupreempt_trace *trace);
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#endif /* __KERNEL__ */
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#endif /* __LINUX_RCUPREEMPT_TRACE_H */
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