Re: [patch 4/9] jffs2: force the jffs2 GC daemon to behave a bit better

[Aras Vaichas <arasv@magtech.com.au>]

Ricard Wanderlof wrote:
> On Wed, 11 Feb 2009, akpm@linux-foundation.org wrote:
>
>   
>> I've noticed some pretty poor behavior on OLPC machines after bootup, when
>> gdm/X are starting.  The GCD monopolizes the scheduler (which in turns
>> means it gets to do more nand i/o), which results in processes taking much
>> much longer than they should to start.
>>     
>
> Can't really comment on how well the patch works, but we've also noticed a 
> similar slowdown on our systems during startup, so the idea as such is 
> welcome at any rate.
>   
I just posted a message to linux-arm-kernel regarding a similar problem 
I have an at91rm9200 based machine with NAND and JFFS2.

I suspected that garbage collection was causing delays of up to 3+ 
seconds during which time my watchdog patting daemon was not being 
scheduled ...

This was causing the watchdog timer to reset my machine but *only* when 
it was under significant NAND load  i.e. boot time, loading up the main 
application while GCD was running.

My solution was to double the watchdog timeout.

Aras

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