linux-kernel - Re: xfsaild causing 30+ wakeups/s on an idle system since 2.6.25-rcX

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Date:	Mon, 18 Feb 2008 11:41:39 +0200
From:	Török Edwin <edwintorok@...il.com>
To:	David Chinner <dgc@....com>
CC:	Oliver Pinter <oliver.pntr@...il.com>, xfs@....sgi.com,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Christoph Lameter <clameter@....com>,
	Christoph Hellwig <hch@...radead.org>
Subject: Re: xfsaild causing 30+ wakeups/s on an idle system since 2.6.25-rcX

David Chinner wrote:
> On Sun, Feb 17, 2008 at 05:51:08PM +0100, Oliver Pinter wrote:
>   
>> On 2/17/08, Török Edwin <edwintorok@...il.com> wrote:
>>     
>>> Hi,
>>>
>>> xfsaild is causing many wakeups, a quick investigation shows
>>> xfsaild_push is always
>>> returning 30 msecs timeout value.
>>>       
>
> That's a bug

Ok. Your patches fixes the 30+ wakeups :)

> , and has nothing to do with power consumption. ;)
>   

I suggest using a sysctl value (such as
/proc/sys/vm/dirty_writeback_centisecs), instead of a hardcoded default
1000.
That would further reduce the wakeups.

>
> I only managed to reproduce this on a lazy superblock counter
> filesystem (i.e.  new mkfs and recent kernel), 

The filesystem was created in July 2007

> Can you see if the patch below fixes the problem.

Yes, it reduces wakeups to 1/sec.

Thanks,
--Edwin
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