is it the future?

[Joonas Sarajärvi]

2014-09-14 0:26 GMT+03:00 Lars E. Pettersson <lars at homer.se>:
> On 09/12/14 21:12, Kevin Fenzi wrote:
>> The amount of memory and i/o is trivial, IMHO.
>
>
> Trivial? Take a look at my nine month old bug report, that has received no
> response whatsoever form the systemd maintainers, about the sluggishness of
> the journal compared to the good old text based log files.
>
> <https://bugzilla.redhat.com/show_bug.cgi?id=1047719>
>
> Even 'systemctl status some_service' take way too long time due to the
> sluggish journal.
>
It is not slow if you have little journal content, as you would in
cases where you prefer plain-text logs and set journald to not keep a
persistent log. At least in my experience, even a Raspberry pi with
less than 200 MiB of RAM can easily handle it.

If you have a large amount of content in the journal, accessing it
takes a bit time. I tend to limit the persistent journal size to
something like a few hundred megabytes. Then it can still store many
months worth of data, but performance of journalctl and systemd status
stay reasonable.

At least for me, most of the journal slowness seems to happen when the
journal data is not cached by the kernel. For example, running
systemctl status postgresql took something like 8 seconds on the first
run, but less than 10 ms on the next one.

- Joonas