Re: [tip:core/rcu] Revert "rcu: Decrease memory-barrier usage based on semi-formal proof"

[Yinghai Lu <yinghai@kernel.org>]

On 05/19/2011 02:37 PM, tip-bot for Paul E. McKenney wrote:
> Commit-ID:  80d02085d99039b3b7f3a73c8896226b0cb1ba07
> Gitweb:     http://git.kernel.org/tip/80d02085d99039b3b7f3a73c8896226b0cb1ba07
> Author:     Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> AuthorDate: Thu, 12 May 2011 01:08:07 -0700
> Committer:  Ingo Molnar <mingo@elte.hu>
> CommitDate: Thu, 19 May 2011 23:25:29 +0200
> 
> 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 <mingo@elte.hu>
> ---
>  Documentation/RCU/trace.txt |   17 ++++--
>  kernel/rcutree.c            |  130 ++++++++++++++++++++++++------------------
>  kernel/rcutree.h            |    9 ++-
>  kernel/rcutree_plugin.h     |    7 +-
>  kernel/rcutree_trace.c      |   12 ++--
>  5 files changed, 102 insertions(+), 73 deletions(-)
> 

current tip/master that have this reverting and without setting DEBUG_LOCKING_API_SELFTESTS

still get delay

[   35.419453] cpu_dev_init done
[  128.981770] memory_dev_init done

should take only 3 or 4 seconds.

Thanks

Yinghai