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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/linux/sched.h
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/linux/sched.h')
-rw-r--r--include/linux/sched.h5
1 files changed, 5 insertions, 0 deletions
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 {
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