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

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Date:	Fri, 20 May 2011 16:16:28 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	paulmck@...ux.vnet.ibm.com
CC:	linux-kernel@...r.kernel.org, mingo@...hat.com, hpa@...or.com,
	tglx@...utronix.de, mingo@...e.hu,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:core/rcu] Revert "rcu: Decrease memory-barrier usage based
 on semi-formal proof"

On 05/20/2011 04:14 PM, Paul E. McKenney wrote:
> On Fri, May 20, 2011 at 04:09:22PM -0700, Yinghai Lu wrote:
>> On 05/20/2011 03:42 PM, Paul E. McKenney wrote:
>>> On Fri, May 20, 2011 at 02:04:06PM -0700, Yinghai Lu wrote:
>>>> 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@...ux.vnet.ibm.com>
>>>>> AuthorDate: Thu, 12 May 2011 01:08:07 -0700
>>>>> Committer:  Ingo Molnar <mingo@...e.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@...e.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.
>>>
>>> Thank you for checking this out.
>>>
>>> This is with the same configuration you sent earlier?  (Other than the
>>> DEBUG_LOCKING_API_SELFTESTS, of course.)
>>>
>>
>> 8 socket westmere-ex. and compiled with gcc from opensuse 11.3.
>>
>> if compile kernel from fedora 14, there will be not delay.
> 
> Thank you for the info.  Could you please send me the .config files from
> both builds?

the same one i sent out before, but let DEBUG_LOCKING_API_SELFTESTS disabled.

Thanks
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