[systemd-devel] [Patch 0/5] support for logging the unit of user session units

[Mirco Tischler]

2013/1/18 Zbigniew Jędrzejewski-Szmek <zbyszek at in.waw.pl>

> Hi,
> I had a look at the your patches (without actually running them :).
> I started with a few cleanups, I'll post them as replies to this letter.
> Then I had a better look at the logic of USER_UNIT and I have a few
> questions.
>
> Hi
Thanks for having a look.

> -#define log_full_unit(level, unit, ...) log_meta_object(level,
> __FILE__, __LINE__, __func__, "UNIT=", unit, __VA_ARGS__)
> +#define log_full_unit(level, unit, ...) log_meta_object(level, __FILE__,
> __LINE__, __func__, getpid() == 1 ? "UNIT=" : "USER_UNIT=", unit,
> __VA_ARGS__)
> +#define log_struct_unit(level, unit, ...) log_struct(level, getpid() == 1
> ? "UNIT=%s" : "USER_UNIT=%s", unit, __VA_ARGS__)

Are all those calls to getpid() efficient? Is the result cached or does
> each one generate a system call?
>
>  According to man 2 getpid the result is cached, which btw Linus calls a
"totally useless optimization" ;)
http://yarchive.net/comp/linux/getpid_caching.html

+        if (!endswith(unit, ".service") &&
> +            !endswith(unit, ".socket") &&
> +            !endswith(unit, ".mount") &&
> +            !endswith(unit, ".swap"))
> +                return 0;
>
> +        if (!endswith(unit, ".service") &&
> +            !endswith(unit, ".socket"))
>
> Do those conditions make sense? Aren't the messages logged for
> all types of units (at least under debug or error conditions)
> by systemd itself?
>
> The the first four conditions already exist in the current code. I wasn't
sure if they make sense either but left them in place for now or rather
removed mount and swap units for the user session.

> Zbyszek
>
Mirco
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