Re: [Yaffs] Getting the most out of YAFFS

On Sat, 2006-01-14 at 14:14 -0800, Kent Ryhorchuk wrote:
> Hi all,
>
> I'm new to the list. I've been working with yaffs2 for
> a while and have gotten to know it well. I'm a fan of
> yaffs and like the way it stores information on the
> flash. I have not experienced any functional problems
> that were not the fault bad integration (me!).
>
> I've got it working on a 2GB Samsung NAND flash. This
> flash supports interleaved operation (two chip
> selects) and cached programming (odd and even banks on
> each chip). The host CPU is a 180MHz ARM9 that has a
> dedicated smart media interface with HW ECC
> calculation and DMA.
>
> I started with MTD (Linux 2.6.13) but since have
> bypassed the MTD layer all together and branched out
> on my own page-oriented NAND driver framework. I
> copied the yaffs_mtdif code to integrate my driver.
>
> There are two big problems I am working on solving:
>
> 1. Mount time - by ripping out all the MTD code and
> really optimizing the driver I've got the mount time
> down to a minute. The time budget os 10s to cold-boot
> the entire system. Uh-oh.

Break your flash up into at least two partitions, a root, and the rest
of the system. The root can be smaller and hold the root filesystem so
the system boots up pretty quick, and as it gets going, mount the other
partition in the background so you can get other servives, etc running
without waiting to wade over the bulk of the flash...

> 2. Taking advantage of the chips interleaving and
> cached programming features. My throughput is about
> 1.5 MB/s but I really want to quadruple that or better
> if possible.
>
> What is the current thinking on these two issues?
>
> Regards,
> Kent Ryhorchuk.
>
>
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--
Peter Barada <Peter.B@LogicPD.com>