Date: Wed, 17 Feb 2010 21:51:58 -0500
From: Michael Breuer <mbreuer@majjas.com>
Subject: Re: Hung task - sync - 2.6.33-rc7  w/md6 multicore rebuild in	process
In-reply-to: <20100218023934.GC8897@atrey.karlin.mff.cuni.cz>
To: Jan Kara <jack@suse.cz>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On 2/17/2010 9:39 PM, Jan Kara wrote:
>> On 2/13/2010 11:51 AM, Michael Breuer wrote:
>>      
>> Note: this cleared after about 90 minutes - sync eventually completed.
>> I'm thinking that with multicore enabled the resync is able to starve
>> out normal system activities that weren't starved w/o multicore.
>>      
>    Hmm, it is a bug in writeback code. But as Linus pointed out, it's not really
> clear why it's *so* slow. So when it happens again, could you please sample for
> a while (like every second for 30 seconds) stacks of blocked tasks via
> Alt-Sysrq-W? I'd like to see where flusher threads are hanging... Thanks.
>
> 								Honza
>    
Ok - will do. On rc8 now - and up about 3 days without any issues. If I 
have some time tomorrow I'll force a raid resync and see what happens.
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