I have studied a little the problem enabling verbose printk and I have
seen an intertesting thing.
If I write into yaffs, a yaffs routine writes a printk message
"yaffs_write_super" every 5 secs.
In this case, If I use "sync" command from user space, this printk
message vanishes.
I don't understand why this routine taht runs every 5secs does not
sync, so all could be OK.
I have to study the problem in more detail.

Bye,
Paolo

On Thu, Sep 17, 2009 at 11:02 PM, Charles Manning
<manningc2@actrix.gen.nz> wrote:
> On Thursday 17 September 2009 19:17:55 Paolo Minazzi wrote:
>> Hi,
>> I have searched into the old posts and googling but I have not found any
>> answer. I use an ARM board with NAND flash 1GB.
>> I'm trying to use yaffs.
>> I have done some tests and it seems much better that JFFS2 (regarding
>> mount time).
>>
>> I have only a doubt.
>>
>> My system mount automatically yaffs2 file system at startup.
>>
>> If I write into yaffs2 partition and I use "umount" or "sync" before
>> turn off the power, the successive mount command is very fast (about
>> 0.1sec)
>> If I write into yaffs2 partition and I don't use "umount" or "sync"
>> before turn off the power, the successive mount command is very slow
>> (about 13sec)
>>
>> A solution could be to have a background task :
>> while [ 1 ]; do sync; sleep 1; done
>> but obviously it is not good.
>>
>> I have not found any configuration option that solve this problem.
>
> There isn't any.
>
>>
>> Have you got some suggestion ?
>
> You might verify that your flash drivers are fast. Flash driver speed is the
> most critical part of getting a fast flash file system.
>
> There is one feature that I have "paper designed" but not yet written and that
> is writing "block summaries". These would radically improve mount times when
> there is no checkpoint (sync/umount) data.
>
> I would expect that to speed things to two seconds or so in your case.
>
>
> -- Charles
>