Re: Great jffs2 speedup

["Jörn Engel" <joern@wohnheim.fh-wedel.de>]

On Thu, 29 September 2005 11:52:57 +0200, Ferenc Havasi wrote:
> >
> >How is the CS information found during mount?  Special location?
> 
> There is two way (can be selected via kernel config):
> 
> The first way stores a reference in the first (usable) erase block. (If
> it is not free, it moves the data to somewhere else, and reserve). It
> stores only a reference to it at umount, and a "mount-log" at mount
> (just to mark that it is invalid in case of unclean umount). It means
> one page write at mount, one page write at umount. If the erase block
> consist 16 pages than it is necesarry to erase the first erase block
> after every 8 mounts. So the typical timelife of it is about 8*100.000
> mounting, I think it is big enough.
> 
> The other way is to specify the cenratlized summary information with
> mount option (not to use the first erase block to store this pointer).
> In this case some other system have to store it (typically on an other
> file system), and the new location after umount can be read using sysfs.

Sounds sane.  100k clean unmounts should be fine for most people.  I
know a couple of testers that would immediatly create a simple
while true; do mount mtd0 /mnt -t jffs2; umount /mnt; done
testcase just to prove you wrong, but apart from that...

Jörn

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