f2fs on GTA02

[Peter Viskup]

On 12/06/2012 10:19 PM, Phil Vandry wrote:
> Hello Freerunner users,
>
> I am interested in using the new f2fs filesystem created by Kim 
> Jaegeuk at Samsung on the µSD cards of a bunch of GTA02s. Right now 
> it's undergoing testing in linux-next and there are several fresh 
> discussion threads about it on lkml. I intend to wait until the code 
> has stabilized a bit before making the attempt.
>
> First, is this a good idea? Also, is anyone else interested?
>
> The problem is that the code only compiles against recent Linux 
> kernels and the newest kernel available for GTA02 is 2.6.39. I see two 
> options:
>
> 1. Get Linux 3.7 working on the GTA02
>
> 2. Get f2fs working on Linux 2.6.39
>
> Both options are challenging but I have to go for #2 because I don't 
> have the knowledge to do #1.
>
> For #1: There are quite a few differences between upstream 2.6.39 and 
> om-gta02-2.6.39 kernels. Some of the patches I understand and could 
> re-apply against a more recent kernel, some of them have already been 
> integrated upstream, but others are mysterious to me and even if I 
> could apply them I can't guess whether or not they ought to still be 
> applied. One big issue is that the glamo driver is not present 
> upstream (and ar6000 also?).
>
> For #2: I have already prepared a patch to backport f2fs to 
> 2.6.34/2.6.39 but there have been quite a lot of changes in the vfs 
> and other areas in the intervening time. The patch is 817 lines long. 
> Most of it is straightforward, though there were one or two tricky 
> bits. The only thing I have achieved so far is getting it to compile 
> with no errors and no warnings. That's a start, but it's not a 
> guarantee that the filesystem will actually work!
>
> A significant problem with #2 is maintenance and bug fixes going 
> forward. I would have to backport all future changes to f2fs.
>
> Anyway, for the information of anyone who's interested, I plan to at 
> least give option #2 a try and see if I might be lucky :-)
>
> -v
>
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Hi Phil,
would be great to see how it performs. I would like to ask you to 
publish outcomes of your performance tests on the openmoko wiki [1] or 
here on the list. I found UBIFS an great filesystem for the OpenMoko 
with great performance and less memory requirements.
QtMoko with UBIFS needed approximately 10MB (don't remember the real 
number - it could be double) less memory than image with JFFS2.
On devices with such small amount of memory as OpenMoko have the 
optimization of memory use is important - not only read/write speed. 
Today's smartphones have much more memory and I am curious if Kim did 
take care of minimization of memory structures of this fs.

Looking forward for your reports.

[1] http://wiki.openmoko.org/wiki/UBIFS#Performance

--
Peter Viskup