From: Patrik Lundquist <patrik.lundquist@gmail.com>
To: Marc MERLIN <marc@merlins.org>
Cc: "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: Major HDD performance degradation on btrfs receive
Date: Wed, 24 Feb 2016 11:01:16 +0100 [thread overview]
Message-ID: <CAA7pwKMkrraeCcusTaKDjinKQ5YPgAyRPoKa+66XOZefYhi8Tg@mail.gmail.com> (raw)
In-Reply-To: <20160223172635.GI22487@merlins.org>
On 23 February 2016 at 18:26, Marc MERLIN <marc@merlins.org> wrote:
>
> I'm currently doing a very slow defrag to see if it'll help (looks like
> it's going to take days).
> I'm doing this:
> for i in dir1 dir2 debian32 debian64 ubuntu dir4 ; do echo $i; time btrfs fi defragment -v -r $i; done
[snip]
> Also, should I try running defragment -r from cron from time to time?
I find the default threshold a bit low and defragment daily with "-t
1m" to combat heavy random write fragmentation.
Once in a while I defrag e.g. VM disk images with "-t 128m" but find
higher thresholds mostly a waste of time.
YMMV.
> But, just to be clear, is there a way I missed to see how fragmented my
> filesystem is without running filefrag on millions of files and parsing
> the output?
I don't think so, and filefrag is slow with heavily fragmented files
because ioctl(FS_IOC_FIEMAP) is called many times with a buffer which
only fits 292 fiemap_extents.
next prev parent reply other threads:[~2016-02-24 10:01 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-22 19:58 Major HDD performance degradation on btrfs receive Nazar Mokrynskyi
2016-02-22 23:30 ` Duncan
2016-02-23 17:26 ` Marc MERLIN
2016-02-23 17:34 ` Marc MERLIN
2016-02-23 18:01 ` Lionel Bouton
2016-02-23 18:30 ` Marc MERLIN
2016-02-23 20:35 ` Lionel Bouton
2016-02-24 10:01 ` Patrik Lundquist [this message]
2016-02-23 16:55 ` Nazar Mokrynskyi
2016-02-23 17:05 ` Alexander Fougner
2016-02-23 17:18 ` Nazar Mokrynskyi
2016-02-23 17:29 ` Alexander Fougner
2016-02-23 17:34 ` Nazar Mokrynskyi
2016-02-23 18:09 ` Austin S. Hemmelgarn
2016-02-23 17:44 ` Nazar Mokrynskyi
2016-02-24 22:32 ` Henk Slager
2016-02-24 22:46 ` Nazar Mokrynskyi
[not found] ` <ce805cd7-422c-ab6a-fbf8-18a304aa640d@mokrynskyi.com>
2016-02-25 1:04 ` Henk Slager
2016-03-15 0:47 ` Nazar Mokrynskyi
2016-03-15 23:11 ` Henk Slager
2016-03-16 3:37 ` Nazar Mokrynskyi
2016-03-16 4:18 ` Chris Murphy
2016-03-16 4:23 ` Nazar Mokrynskyi
2016-03-16 6:51 ` Chris Murphy
2016-03-16 11:53 ` Austin S. Hemmelgarn
2016-03-16 20:58 ` Chris Murphy
2016-03-16 4:22 ` Chris Murphy
2016-03-17 7:00 ` Duncan
2016-03-18 14:22 ` Nazar Mokrynskyi
2016-05-27 1:57 ` Nazar Mokrynskyi
-- strict thread matches above, loose matches on Subject: below --
2016-02-22 19:39 Nazar Mokrynskyi
2016-02-16 4:44 Nazar Mokrynskyi
2016-02-16 9:10 ` Duncan
2016-02-18 18:19 ` Henk Slager
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