On Jun 11, 2014, at 7:21 PM, Dave Chinner <da...@fromorbit.com> wrote:
> On Wed, Jun 11, 2014 at 11:28:54PM +0200, Goffredo Baroncelli wrote: >> Hi all, >> >> I would like to share a my experience about a slowness of systemd when used >> on BTRFS. >> >> My boot time was very high (about ~50 seconds); most of time it was due to >> NetworkManager which took about 30-40 seconds to start (this data came from >> "systemd-analyze plot"). >> >> I make several attempts to address this issue. Also I noticed that sometime >> this problem disappeared; but I was never able to understand why. >> >> However this link >> >> https://bugzilla.redhat.com/show_bug.cgi?id=1006386 >> >> suggested me that the problem could be due to a bad interaction between >> systemd and btrfs. NetworkManager was innocent. > > systemd has a very stupid journal write pattern. It checks if there > is space in the file for the write, and if not it fallocates the > small amount of space it needs (it does *4 byte* fallocate calls!) > and then does the write to it. All this does is fragment the crap > out of the log files because the filesystems cannot optimise the > allocation patterns. > > Yup, it fragments journal files on XFS, too. > > http://oss.sgi.com/archives/xfs/2014-03/msg00322.html > > IIRC, the systemd developers consider this a filesystem problem and > so refused to change the systemd code to be nice to the filesystem > allocators, even though they don't actually need to use fallocate... > > Cheers, > > Dave. > > -- > Dave Chinner > da...@fromorbit.com On Jun 11, 2014, at 7:37 PM, Dave Chinner <da...@fromorbit.com> wrote: > > BTW, the systemd list is subscriber only, so thay aren't going to > see anything that we comment on from a cross-post to the btrfs list. Unless a subscriber finds something really interesting, quotes it, and cross posts it. Chris murphy _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
