On Sat, Apr 05, 2014 at 01:10:13PM +0200, Swâmi Petaramesh wrote: > Le samedi 5 avril 2014 10:12:17 Duncan wrote [excellent performance advice > about disabling Akonadi in BTRFS etc]: > > Thanks Duncan for all this excellent discussion. > > However I'm still rather puzzled with a filesystem for which advice is "if you > want tolerable performance, you have to turn off features that are the default > with any other FS out there (relatime -> noatime) or you have to quit using > this database, or you have to fiddle around with esoteric option such as > disabling COW wich BTW is one of BTRFS most promiment features". OK, a couple of points here: - For the things where you should turn CoW off, they're typically things like databases that do their _own_ CoW handling or similar high-performance reliable transactions/writes, so you generally lose very little there. - I'm not aware, particularly, of any major differences between noatime and relatime in performance on btrfs. (But I may be wrong there). - Given Duncan's discussion of the performance of the semantic desktop, I would suggest turning it off *temporarily* to see if it really is where the difficulty lies. If it turns out that it's unrelated and things still slow down horribly, then at least we've knocked down one theory and need to look elsewhere. If it _is_ related, then that at least gives us a reproducer for the problem, and the people who are skilled in tracking down performance problems have something to look at. It also means that you have a range of things you know you can try if the problem gets really bad (maybe delete the database and rebuild it regularly? mark parts of it nodatacow? maybe autodefrag helps? maybe it's something simple the authors of the database can change?). [snip] > I need a filesystem that fits me, I don't want to have to fit my filesystem :-\ If you truly find btrfs unusable -- which you've said at various points in the past -- then I'm not going to suggest that you keep using it. Maybe something else is genuinely better for you. It's not in the interests of the btrfs community to recommend that people use btrfs when it's not appropriate. That said, it would be good to have your help to try to fix the (apparently quite unusual) problems you're seeing. Part of that is tracking down which bit of software is triggering the issues, and helping to identify what the issues actually are. Sometimes, the hardest problem in fixing bugs is finding someone who can reproduce the bug and test fixes. Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- Ceci n'est pas une pipe: | ---
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