linux-kernel - Re: UBIFS recovery taking too long

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Date:	Tue, 10 Dec 2013 09:25:12 +0200
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Shuah Khan <shuahkhan@...il.com>
CC:	David Mosberger-Tang <dmosberger@...il.com>, dedekind1@...il.com,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: UBIFS recovery taking too long

On 09/12/13 23:30, Shuah Khan wrote:
> Adding ubifs maintainers.
> 
> -- Shuah
> 
> On Mon, Dec 9, 2013 at 1:53 PM, David Mosberger-Tang
> <dmosberger@...il.com> wrote:
>> I've had no luck getting any response from the linux-mtd mailing list
>> regarding the issue reported below.
>> I think it is a very serious issue since it can easily render an
>> embedded system unusable.
>>
>>   --david
>>
>> ---------- Forwarded message ----------
>> From: David Mosberger-Tang <dmosberger@...il.com>
>> Date: Thu, Nov 7, 2013 at 11:44 AM
>> Subject: UBIFS recovery taking too long
>> To: "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>
>>
>>
>> We recently encountered a strange issue where UBIFS recovery is
>> suddenly taking a lot longer than usual (v3.7-based kernel).  In our
>> case, recovery took about 30 seconds.  This caused a serious problem
>> because our watchdog timer was set to 15 seconds, effectively
>> rendering the devices unbootable.
>>
>> Does anybody know what triggers this slow recovery mode?  Also, how
>> can we calculate a worst-case recovery time for a given flash
>> chip-size.

Slowness is probably caused by trying to make free space.  Was the file
system very full?  A smaller journal might help.

Probably the only way to determine worst-case recovery time is to test it.
Worst case conditions are likely to be a full journal and a nearly full file
system.

Ideally you want to capture a file system image that exhibits the slow
behaviour, then you can enable debug messages and see what it is doing.

>>
>> Thanks,
>>
>>   --david
>> --
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> 
> 

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