On 06/30/2013 06:53 PM, Garry T. Williams wrote:
On 6-30-13 19:26:16 Shridhar Daithankar wrote:
Whenever there is a unclean shutdown(which happens a lot in my
case), the next reboot, system comes up relatively at the same speed
but as systemd is starting up daemons, the disk is continuously (and
unusally long) grinding.
I am running archlinux/systemd/kde
I suspect this is, at least in part, related to severe fragmentation
in /home.
I'm wondering if this is affecting myself. I have a big issue with my
data drive slowing down and there being near long periods of high disk
IO that prevent me doing anything else. I've noticed from iotop various
btrfs processes hogging the IO for long periods, e.g.
btrfs-transacti... & btrfs-submit
I've been running kde which has got unusable (not from reboot, but in
general). xfce is less hampered but IO still seems like an issue at
times. Of course, xfce hits different files. I've been using this file
system a couple of months and not defragged before. I started
defragging the various subvolumes a week or two ago - but I did not
realise this was not recursive until this weekend. I've got a python
script running defrag on various files and folders - I can better track
what it is defragging. But it is _slow_ many many minutes for a rarely
accessed folder with little content. Is this normal?
I too had an issue with unclean shutdowns. I, relatively infrequently,
get lockups. However, I had a spate last week which I have yet to
resolve. I wonder if that is related.
I wonder, if I defrag everything on say a weekly basis then will these
performance issues go away? Running a 3.9.3 kernel.
Pete
There are large files in these directories that are updated frequently
by various components of KDE and the Chrome browser. (Firefox has its
own databases that are frequently updated, too.)
~/.local/share/akonadi
~/.kde/share/apps/nepomuk/repository/main/data/virtuosobackend
~/.cache/chromium/Default/Cache
~/.cache/chromium/Default/Media\ Cache
I improved performance dramatically (orders of magnitude) by copying
the database files into an empty file that was modified with:
chattr -C
and renaming to make the files no COW. (Note that this is the only
way to change an existing file to no COW.) I also set the same
attribute on the owning directories so that all new files inherit the
no COW attribute.
I suspect there are other files that fragment badly since I see
periods of high disk activity coming back slowly over a few weeks of
use after making the modifications above. I intend to track them down
and do the same.
Also, see these:
https://btrfs.wiki.kernel.org/index.php/Problem_FAQ#Defragmenting_a_directory_doesn.27t_work
https://btrfs.wiki.kernel.org/index.php/UseCases#How_do_I_defragment_many_files.3F
$ uname -r
3.9.6-200.fc18.x86_64
$
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