[systemd-devel] Excessive (virtual) memory usage of journald

[Kay Sievers]

On Fri, Jun 21, 2013 at 7:50 AM, Holger Freyther <holger at freyther.de> wrote:
> Good Morning,
>
> I had postponed the adoption of systemd due the excessive CPU usage
> of the journald. I am re-evaluating the situation with version 204
> right now and I noticed that the (virtual) address space is getting
> unusual big.
>
> My journald config configuration is:
>
>   [Journal]
>   Storage=volatile
>   RuntimeMaxUse=648K
>
>
> $ cat /proc/`pidof systemd-journald`/status
> ...
> VmPeak:   131108 kB
> VmSize:    90820 kB
> VmLck:         0 kB
> VmPin:         0 kB
> VmHWM:      9308 kB
> VmRSS:      6632 kB
> VmData:      448 kB
> VmStk:       136 kB
> VmExe:       176 kB
> VmLib:      1972 kB
> VmPTE:       106 kB
> VmSwap:        0 kB
> Threads:        1
> ..
>
> The process size is decreasing (I assume when the journal gets
> compacted) so right now I don't think there is a (big) memory
> leak. But then again needing 130mb of address space to manage a
> buffer of 648kb looks quite excessive to me.
>
> Is this a known inefficiency of systemd? What is the reason for
> this behavior?

What's the problem with using address *space*? Address space is not
used memory, file memory mappings are just how things work in general,
they are cheap and should not really matter.

You might want to look at:
  $ sudo pmap -d $(pidof systemd-journald)

to know how much memory is really used.

Kay