On Tuesday, July 02, 2013 01:00:29 PM Duncan wrote: > Just to be clear, your system, your call. I'd never /dream/ of > interfering with that due to the implications for my own system (which is > certainly highly customized even matched against a peer-group of other > gentoo installs =:^). That said... > > I'm guessing what you experiences with the autodefrag mount option was > because you were not in stable-state yet. The original btrfs filesystem > setup and fill was very likely without the flag on[2], so there's quite a > lot of existing fragmentation what would have to be worked thru before > the filesystem gets defragged and you reach stable-state, at which I'd > expect the autodefrag mount option to have little overhead.
Yes, I suspect as much. One of the data parition I have is over an year old and never defragged, /home about 3 months old. and I can see the defragmentation working when run by hand. The initial run on /var(only directories, to defrag metadata) was 6 min. Now that I am running it daily by hand, entire /var(including files, that includes 1.8G pacman cache, few tiny postgresql databases and /var/tmp where kde generates tons of IO) takes about 6-7 min. Despite of my experience with autodefrag, I want to use it because thats the best solution(kinda like autovacuum in postgresql) that keeps things clean, all the time. > > Tho if what you're saying is correct[1] then it may be that the > background defrag thread isn't (io-)niced as I would have expected it to > be. > > But I'd still expect there to be some better performance steady state > after a few mounts gets the basic filesystem defragged. Tho if the > fileystem is heavily fragmented[2], in practice it may well be easier to > backup the filesystem content, do a clean mkfs and mount with autodefrag > and restore from backup, thus ensuring autodefrag is on while filling the > filesystem in the first place, than to wait for autodefrag to reach a > stable system state in normal operation over many mounts. well, I think I will bite the bullet and defrag entire / overnight and repeat the autodefrag mount option. That should work too. Thanks -- Regards Shridhar -- 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
