On Wed, 7 May 2014 04:30:30 -0700 Marc MERLIN <marc@xxxxxxxxxxx> wrote: > > -dusage=85 balances all chunks that up to 85% full. The higher the > > number, the more work that needs to be done. > > Aah, right. I see why it's more work. =20 only makes is process the > few chunks that are up to 20% full which won't be many if your FS > is almost full. It's actually even less work than you imply. Balance only has to rewrite the actual content, not the empty space in the chunk. So 20% full means it's only writing 20% of the (possible/full) content, thus only taking 20% of the time to rewrite that chunk that it'd take to rewrite a full chunk. Which is why a usage=5 or 20 goes so fast, even if the system's actually mostly empty but is all allocated. With a 20% full chunk it's rewriting five chunks into one; at 5%, it's rewriting 20 chunks into one. That goes pretty fast, even if there's a bunch of them to write! -- Duncan - No HTML messages please, as they are filtered as spam. "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 majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
