I've had a very similar issue with the performance of my laptop dropping to very low levels, eventually solved by uninstalling Snapper, deleting snapshots, and then defragmenting the drive.
This seems to be a common concern, I also had it happen on my desktop. Dmitry --- Thank you, Dmitry Kudriavtsev https://dkudriavtsev.xyz inexpensivecomputers.net ⠀⠀⠀⠀⠀⠀⠀⣸⣧⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⣰⣿⣿⣆⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⣀⡙⠿⣿⣿⣆⠀⠀⠀⠀⠀Hey, did you hear about that cool new OS? It's called ⠀⠀⠀⠀⣰⣿⣿⣷⣿⣿⣿⣆⠀⠀⠀⠀Arch Linux. I use Arch Linux. Have you ever used Arch ⠀⠀⠀⣰⣿⣿⣿⡿⢿⣿⣿⣿⣆⠀⠀⠀Linux? You should use Arch Linux. Everyone uses Arch! ⠀⠀⣰⣿⣿⣿⡏⠀⠀⢹⣿⣿⠿⡆⠀⠀Check out i3wm too! ⠀⣰⣿⣿⣿⡿⠇⠀⠀⠸⢿⣿⣷⣦⣄⠀ ⣼⠿⠛⠉⠀⠀⠀⠀⠀⠀⠀⠀⠉⠛⠿⣦ September 19 2017 11:38 PM, "Dave" <davestechs...@gmail.com> wrote: >> On Thu 2017-08-31 (09:05), Ulli Horlacher wrote: >>> When I do a >>> btrfs filesystem defragment -r /directory >>> does it defragment really all files in this directory tree, even if it >>> contains subvolumes? >>> The man page does not mention subvolumes on this topic. >> >> No answer so far :-( >> >> But I found another problem in the man-page: >> >> Defragmenting with Linux kernel versions < 3.9 or >= 3.14-rc2 as well as >> with Linux stable kernel versions >= 3.10.31, >= 3.12.12 or >= 3.13.4 >> will break up the ref-links of COW data (for example files copied with >> cp --reflink, snapshots or de-duplicated data). This may cause >> considerable increase of space usage depending on the broken up >> ref-links. >> >> I am running Ubuntu 16.04 with Linux kernel 4.10 and I have several >> snapshots. >> Therefore, I better should avoid calling "btrfs filesystem defragment -r"? >> >> What is the defragmenting best practice? >> Avoid it completly? > > My question is the same as the OP in this thread, so I came here to > read the answers before asking. However, it turns out that I still > need to ask something. Should I ask here or start a new thread? (I'll > assume here, since the topic is the same.) > > Based on the answers here, it sounds like I should not run defrag at > all. However, I have a performance problem I need to solve, so if I > don't defrag, I need to do something else. > > Here's my scenario. Some months ago I built an over-the-top powerful > desktop computer / workstation and I was looking forward to really > fantastic performance improvements over my 6 year old Ubuntu machine. > I installed Arch Linux on BTRFS on the new computer (on an SSD). To my > shock, it was no faster than my old machine. I focused a lot on > Firefox performance because I use Firefox a lot and that was one of > the applications in which I was most looking forward to better > performance. > > I tried everything I could think of and everything recommended to me > in various forums (except switching to Windows) and the performance > remained very disappointing. > > Then today I read the following: > > Gotchas - btrfs Wiki > https://btrfs.wiki.kernel.org/index.php/Gotchas > > Fragmentation: Files with a lot of random writes can become > heavily fragmented (10000+ extents) causing excessive multi-second > spikes of CPU load on systems with an SSD or large amount a RAM. On > desktops this primarily affects application databases (including > Firefox). Workarounds include manually defragmenting your home > directory using btrfs fi defragment. Auto-defragment (mount option > autodefrag) should solve this problem. > > Upon reading that I am wondering if fragmentation in the Firefox > profile is part of my issue. That's one thing I never tested > previously. (BTW, this system has 256 GB of RAM and 20 cores.) > > Furthermore, on the same BTRFS Wiki page, it mentions the performance > penalties of many snapshots. I am keeping 30 to 50 snapshots of the > volume that contains the Firefox profile. > > Would these two things be enough to turn top-of-the-line hardware into > a mediocre-preforming desktop system? (The system performs fine on > benchmarks -- it's real life usage, particularly with Firefox where it > is disappointing.) > > After reading the info here, I am wondering if I should make a new > subvolume just for my Firefox profile(s) and not use COW and/or not > keep snapshots on it and mount it with the autodefrag option. > > As part of this strategy, I could send snapshots to another disk using > btrfs send-receive. That way I would have the benefits of snapshots > (which are important to me), but by not keeping any snapshots on the > live subvolume I could avoid the performance problems. > > What would you guys do in this situation? > -- > 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 -- 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
