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

@@ -99,11 +99,18 @@ o "qp" indicates that RCU still expects a quiescent state from
o "dt" is the current value of the dyntick counter that is incremented
when entering or leaving dynticks idle state, either by the
scheduler or by irq. This number is even if the CPU is in
dyntick idle mode and odd otherwise. The number after the first
"/" is the interrupt nesting depth when in dyntick-idle state,
or one greater than the interrupt-nesting depth otherwise.
The number after the second "/" is the NMI nesting depth.
scheduler or by irq. The number after the "/" is the interrupt
nesting depth when in dyntick-idle state, or one greater than
the interrupt-nesting depth otherwise.
This field is displayed only for CONFIG_NO_HZ kernels.
o "dn" is the current value of the dyntick counter that is incremented
when entering or leaving dynticks idle state via NMI. If both
the "dt" and "dn" values are even, then this CPU is in dynticks
idle mode and may be ignored by RCU. If either of these two
counters is odd, then RCU must be alert to the possibility of
an RCU read-side critical section running on this CPU.
This field is displayed only for CONFIG_NO_HZ kernels.