Marc Joliet posted on Sat, 05 Dec 2015 15:11:51 +0100 as excerpted: > I do think it's interesting that compression (even with LZO) seems to > have offset the extra space wastage caused by autodefrag.
I've seen (I think) you mention that twice now. Perhaps I'm missing something... How does autodefrag trigger space wastage? What autodefrag does is watch for seriously fragmented files and queue them up for later defrag by a worker thread. How would that waste space? Unless of course you're talking about breaking reflinks to existing snapshots or other (possibly partial) copies of the file. But I'd call that wasting space due to the snapshots storing old copies, not due to autodefrag keeping the current copy defragmented. And reflinks are saving space by effectively storing parts of two files in the same extent, not autodefrag wasting it, as the default on a normal filesystem would be separate copies, so that's the zero-point base, and reflinks save from it, with autodefrag therefore not changing things from the zero- point base. No snapshots, no reflinks, autodefrag no longer "wastes" space, so it's not autodefrag's wastage in the first place, it's the other mechanisms' saving space. >From my viewpoint, anyway. I'd not ordinarily quibble over it one way or the other if that's what you're referring to. But just in case you had something else in mind that I'm not aware of, I'm posting the question. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
