Re: Great jffs2 speedup

["Artem B. Bityutskiy" <dedekind@yandex.ru>]

Ferenc Havasi wrote:
> 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.
This spoils the overall wear-leveling, which is no good. But should work.

> 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.
This also spoils wear-levelling...

And I don't like CS in general as it is not tolerant to unclean 
reboots... Albeit, if this does not matter to a specific system - this 
will work.

Nevertheless, I don't believe CS will make JFFS2 usable on 256MB 
flashes, due to memory consumprion issues. Nor it will not (IMO) make it 
scalable, which is sad :-(

-- 
Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.