Messages in this thread | | | Date | Tue, 01 Apr 2008 08:26:37 +0300 | From | Artem Bityutskiy <> | Subject | UBIFS vs Logfs (was [RFC PATCH] UBIFS - new flash file system) |
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I've renamed the thread because I do not like this flamish discussion to me mixed with the technical one.
Jörn Engel wrote: > Shiny numbers! Performance has improved significantly in the last six > month. Still worth a closer look. We'll re-run them. Does logfs support write-back? Does it support compression? Is this patch the right one we should look at:
>> 3. logfs does not seem to have bad-block handling. > > Bad blocks at mkfs time are handled, blocks turning bad later on aren't > yet.
This basically means it is unfinished. Handling dynamic bad blocks is a *must* if you are going to work on NAND, especially on MLC NAND which are not as reliable as SLC.
I think you should bluntly say about this when you submit patches to prevent people from starting using it in production.
UBI handles I/O errors and gracefully recovers the data. And it will not be easy to do this in LogFS at all. If you have write error in the middle of an eraseblock, you have to recover data which means correcting all the indexing data structures which refer the data you recover. Correcting them may require garbage collection, because you have to update them out of place. And what do you do if you are already in the middle of doing garbage-collection?
In other words, I believe it will take a lot of time and efforts to implement this. And any speculation about the number of lines of code makes no sense before you finish your work.
>> 4. logfs does not seem to have wear-leveling. > It does. Could you please point the core functions which implement this and shortly describe the algorithm?
I grep'ed for "wear" and "leveling" and found only one match. Where should I look at?
-- Best Regards, Artem Bityutskiy (Артём Битюцкий) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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