From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner+willy=40w.ods.org-S932560AbWGMGNL@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S932560AbWGMGNL (ORCPT <rfc822;willy@w.ods.org>);
	Thu, 13 Jul 2006 02:13:11 -0400
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932559AbWGMGNK
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Thu, 13 Jul 2006 02:13:10 -0400
Received: from nf-out-0910.google.com ([64.233.182.189]:48881 "EHLO
	nf-out-0910.google.com") by vger.kernel.org with ESMTP
	id S932540AbWGMGNJ (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Thu, 13 Jul 2006 02:13:09 -0400
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
        s=beta; d=gmail.com;
        h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references;
        b=RZBB/fEoZ9pY8YUATZJz5i10GG+kpjTvIRgxIaPkgyTRk/JrgAb8OKwE9hAYCrm3tP++2SvdEwxnMJLg5s/rWh1ekTyaHGZ9zg/zB7MmceYgoIvqJlsI5ojX86qsgsj66bA2saaXcv/gFb/KkDqs5zwGbLh2Ny8L6RnEVNMaJdQ=
Message-ID: <787b0d920607122313u60a97698m2c4f75f93562d67d@mail.gmail.com>
Date: Thu, 13 Jul 2006 02:13:07 -0400
From: "Albert Cahalan" <acahalan@gmail.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] Use uname not sysctl to get the kernel revision
Cc: ak@suse.de, tytso@mit.edu, ebiederm@xmission.com, drepper@redhat.com,
       arjan@infradead.org, rdunlap@xenotime.net, akpm@osdl.org,
       linux-kernel@vger.kernel.org, libc-alpha@sourceware.org
In-Reply-To: <787b0d920607122309i364a3110re9907a947f907735@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
References: <787b0d920607122200m4785f7ddmddf40c079a7460cb@mail.gmail.com>
	 <44B5DD41.90705@zytor.com>
	 <787b0d920607122309i364a3110re9907a947f907735@mail.gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
X-Mailing-List: linux-kernel@vger.kernel.org

On 7/13/06, Albert Cahalan <acahalan@gmail.com> wrote:
> On 7/13/06, H. Peter Anvin <hpa@zytor.com> 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.