From: john stultz <johnstul@us.ibm.com>
Subject: Re: ext4 dbench performance with CONFIG_PREEMPT_RT
Date: Tue, 13 Apr 2010 20:04:50 -0700
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Cc: linux-ext4@vger.kernel.org, Mingming Cao <cmm@us.ibm.com>,
	keith maanthey <kmannth@us.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@elte.hu>, Darren Hart <dvhltc@us.ibm.com>,
	djwong <djwong@linux.vnet.ibm.com>
To: tytso@mit.edu
In-Reply-To: <20100408211054.GB1849@thunk.org>
Sender: linux-ext4-owner@vger.kernel.org

On Thu, 2010-04-08 at 17:10 -0400, tytso@mit.edu wrote:
> On Thu, Apr 08, 2010 at 01:41:57PM -0700, john stultz wrote:
> > 
> > I'll continue to play with your patch and see if I can con some some
> > folks with more interesting storage setups to do some testing as well.
> 
> You might want to ask djwong to play with it with his nice big
> machine.  (We don't need a big file system, but we want as many CPU's
> as possible, and to use his "mailserver" workload to really stress the
> journal.  I'd recommend using barrier=0 for additional journal
> lock-level stress testing, and then try some forced sysrq-b reboots
> and then make sure that the filesystem is consistent after the journal
> replay.)

So I did the above on a 16way that I borrowed from Keith and Darrick.
Got about 5 power-cycles and the journal was recovered and reported
clean by fsck on bootup each time.

So, again, doesn't prove its right, but nothing blew up. 

thanks
-john