From 80d02085d99039b3b7f3a73c8896226b0cb1ba07 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 12 May 2011 01:08:07 -0700 Subject: Revert "rcu: Decrease memory-barrier usage based on semi-formal proof" This reverts commit e59fb3120becfb36b22ddb8bd27d065d3cdca499. 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 --- Documentation/RCU/trace.txt | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) (limited to 'Documentation/RCU') diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index 8173cec473a..c078ad48f7a 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -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. -- cgit v1.2.3-70-g09d2