Re: [PATCH] Use uname not sysctl to get the kernel revision

[Albert Cahalan]

On 7/13/06, Albert Cahalan <acahalan@xxxxxxxxx> wrote:
> On 7/13/06, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> > Albert Cahalan wrote:
> > >>
> > >> The numerical namespace for sysctl is unsalvagable imho. e.g.
> > >> distributions regularly break it because there is no central
> > >> repository of numbers so it's not very usable anyways in practice.
> > >
> > > Huh? How exactly is this different from system call numbers,
> > > ioctl numbers, fcntl numbers, ptrace command numbers, and every
> > > other part of the Linux ABI?
> > >
> >
> > Mostly because some branches of the sysctl tree have dynamic content
> > which is hard to marshal into a numeric form.
>
> Dynamic content is no problem. FreeBSD uses sysctl
> to implement their "ps" program. The process info comes
> out of sysctl now. The sysctl man page has an example.
>
> Non-numeric data is more troublesome. FreeBSD has
> a syscall that will take text (still faster than /proc/sys),
> and another that will convert the text representation
> into numeric form for later high-performance use.
>
> Look up all 3 calls here, in section 2:
> http://www.freebsd.org/cgi/man.cgi?manpath=FreeBSD+7.0-current

Excuse me, it's in section 3. I don't know if they use
a _sysctl like we do or what. Anyway, they claim that
the numeric version is several times faster, so I don't
think this is just a libc wrapper around /proc.
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