Sysctl as a Service, or: making sysctl(3) more friendly for monitoring systems

[Warner Losh]

On Mon, Dec 12, 2016 at 6:34 AM, Ed Schouten <ed at nuxi.nl> wrote:
> Hi Jonathan,
>
> 2016-12-11 21:12 GMT+01:00 Jonathan Anderson <jonathan at freebsd.org>:
>> Rather than doing lots of system calls to
>> enumerate clearly-related sysctl values, it would be very cool to do one
>> system call and then inspect the resulting data structure in memory.
>
> I'm not sure it's worth tackling this problem at this time. My current
> version of the exporter is already pretty fast:
>
> $ time ./prometheus_sysctl_exporter | wc -l
>         0.00 real         0.00 user         0.00 sys
>     3162
>
> If our sysctl tree would get substantially larger at some point, we
> should of course revisit this.

That sounds cool. I'd love to see what you came up with to get those results.

While we're here... there's one thing I'd love to see from  a
hypothetical /dev/sysctl... When a sysctl value changes (or some
subset), I'd like it to appear on a read-channel. That way, I could
monitor temperature w/o needing to constantly poll for changes, for
example.

Warner