[systemd-devel] Slow startup of systemd-journal on BTRFS

[Kai Krakow]

Goffredo Baroncelli <kreijack at libero.it> schrieb:

> On 06/14/2014 10:13 PM, Kai Krakow wrote:
>> Take care to enable all needed services to enable defrag... If your
>> services make use of journal file loading these files should also become
>> part of the process. You can check with
>> "/usr/lib/systemd/systemd-readahead analyze". The state is stored in
>> /.readahead.
>> 
> I have enabled all the services (collect, replay, done), but I was unable
> to see any gain.

I don't think you can actually enable the "done" service because it is 
static... But if it placed a symlink in /etc/systemd that is probably wrong 
and you should undo it. It is automatically activated a few seconds after 
booting is done to store the collected data for replaying on next reboot.

Check with "find /etc/systemd -name '*readahead*' -type l"...

> I don't know why but system.journal is not considered by readahead:
> 
> # /usr/lib/systemd/systemd-readahead analyze | grep journal
> 
> 
>    100% ( 1)          770: /etc/systemd/journald.conf
>     50% ( 1)      4194304:
>     /var/log/journal/36f10f5379ec4a1398ac303a0ce20fd0/user-997.journal
>     50% ( 1)      4194304:
>     /var/log/journal/36f10f5379ec4a1398ac303a0ce20fd0/user-1000.journal

I tried that on my system and it looks vice-versa somehow:

$ sudo /usr/lib/systemd/systemd-readahead analyze|fgrep journal
   100% ( 1)          812: /etc/systemd/journald.conf
   100% ( 1)      8388608: 
/var/log/journal/121b87ca633e8ac0016656680000001b/system.journal

Strange... ;-)

To get back to your performance problem: Did you try "systemctl enable 
bootchart" and then (after a reboot) look at the png generated in /run/log 
(at least in my system it is placed there, look at the configs if in doubt). 
It can give some interesting clues about why a service starts late or takes 
long to execute.

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