2008/7/30 Wookey <
wookey@wookware.org>
> On 2008-07-29 12:53 +0800, alex z wrote:
> > Hi All,
> >
> > Our nand flash driver is really low, so it takes 4 minutes to mount
> after
> > not clear umount.
> > mini-UPS is impossible, my system is a handheld product. :)
>
> Some battery-monitoring to make sure that a clean shutdown occurs when
> the battery is low, but before the CPU/flash actually starts
> operating? Is the problem one of coming back from sleep perhaps, when
> the battery is actually too flat to allow that?
Yes, but the most situation is that our system is just buggy now, so
somethings have to reset system without normal shutdown. Ashamed!! :)
>
>
> > Is it possible that don't call yaffs_ScanBackwards after not clear
> umount?
> > It really kills time.
>
> No, that bit is fundamental.
>
> > Can I use this solution to reduce the mounting time (after normal
> umount
> > or not clear umount):
> > 1) assume the size of yaffs2 partition is 3G, it's called mypartition.
> > 2) create a file which is called myfile and its size is 2.9G into
> > mypartition
> > 3) after mount mypartition, then mount myfile as vfat filesystem.
> > 4) read and write files from/to vfat filesystem.
> >
> > Any comment?
>
> As someone explained this is not how flash filesytsenms work.
> Can you split your filesystem up into smaller chunks? so the system
> mounts first, then data is mounted (so the user gets some feedback?)
Yes, we use squashfs as rootfs. But the data filesystem is yaffs2, because
we have to put many files into a large partition.
>
> Also you should work on optimising your nand driver. As Charles says
> 4mins is pretty slow - what is the CPU/speed?
The CPU speed is 400 MHz, and yes, our nand driver is pretty slow, because
we modified the mtdblock.c to support wear leveling. So, we can put VFAT
filesystem on the nand flash.
and how is it interfaced to
> the flash?
8BIts data lines interfaced to Nand flash.
> You could also up the chunk size from 2K to 4K. If you have
> a small number of large files then bigger chunks is a good tradeoff.
Thanks so much for your tip, I will try it. We have many 3MB files on this
partition, is it your tip will help?
Alex
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