Revert "rcu: Decrease memory-barrier usage based on semi-formal proof"

This reverts commit e59fb3120b.

This reversion was due to (extreme) boot-time slowdowns on SPARC seen by
Yinghai Lu and on x86 by Ingo
.
This is a non-trivial reversion due to intervening commits.

Conflicts:

	Documentation/RCU/trace.txt
	kernel/rcutree.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Paul E. McKenney
2011-05-12 01:08:07 -07:00
committed by Ingo Molnar
parent 11c476f31a
commit 80d02085d9
5 changed files with 102 additions and 73 deletions

View File

@@ -84,9 +84,11 @@
* Dynticks per-CPU state.
*/
struct rcu_dynticks {
int dynticks_nesting; /* Track irq/process nesting level. */
int dynticks_nmi_nesting; /* Track NMI nesting level. */
atomic_t dynticks; /* Even value for dynticks-idle, else odd. */
int dynticks_nesting; /* Track nesting level, sort of. */
int dynticks; /* Even value for dynticks-idle, else odd. */
int dynticks_nmi; /* Even value for either dynticks-idle or */
/* not in nmi handler, else odd. So this */
/* remains even for nmi from irq handler. */
};
/* RCU's kthread states for tracing. */
@@ -282,6 +284,7 @@ struct rcu_data {
/* 3) dynticks interface. */
struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */
int dynticks_snap; /* Per-GP tracking for dynticks. */
int dynticks_nmi_snap; /* Per-GP tracking for dynticks_nmi. */
#endif /* #ifdef CONFIG_NO_HZ */
/* 4) reasons this CPU needed to be kicked by force_quiescent_state */