[systemd-devel] journal fragmentation on Btrfs

[Chris Murphy]

On Mon, Apr 17, 2017 at 10:05 PM, Andrei Borzenkov <arvidjaar at gmail.com> wrote:

> strace -p $(pgrep systemd-journal)
>
> You will not see actual writes as file is memory mapped, but it
> definitely does not do any fsync() every so often.

https://paste.fedoraproject.org/paste/oVT-tsU2sBOdTJaZxGua-15M1UNdIGYhyRLivL9gydE=

That's just a partial, but the complete output captured for a couple
minutes doesn't contain an fsync.

Then I did this for 8 minutes, strace -c -f -p $(pgrep systemd-journal)

https://paste.fedoraproject.org/paste/Uzc2KhkkaqLOU8USLd38B15M1UNdIGYhyRLivL9gydE=

So 6 fsyncs in 8 minutes; more than 1 per 5 minutes, but not nearly as
many as I thought. So maybe as you say it's just memory mapped
activity I'm seeing with state and filefrag.


-- 
Chris Murphy