From owner-freebsd-hackers@FreeBSD.ORG  Wed Apr  9 05:00:56 2003
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id E505D37B41E
	for <hackers@freebsd.org>; Wed,  9 Apr 2003 05:00:56 -0700 (PDT)
Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.86.163])
	by mx1.FreeBSD.org (Postfix) with ESMTP id F408543F3F
	for <hackers@freebsd.org>; Wed,  9 Apr 2003 05:00:55 -0700 (PDT)
	(envelope-from phk@phk.freebsd.dk)
Received: from critter.freebsd.dk (localhost [127.0.0.1])
	by critter.freebsd.dk (8.12.9/8.12.9) with ESMTP id h39C0kZq032991;
	Wed, 9 Apr 2003 14:00:46 +0200 (CEST)
	(envelope-from phk@phk.freebsd.dk)
To: ticso@cicely.de
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Wed, 09 Apr 2003 13:49:58 +0200."
             <20030409114957.GN83126@cicely9.cicely.de> 
Date: Wed, 09 Apr 2003 14:00:46 +0200
Message-ID: <32990.1049889646@critter.freebsd.dk>
cc: hackers@freebsd.org
Subject: Re: realtime problem 
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 09 Apr 2003 12:00:57 -0000

In message <20030409114957.GN83126@cicely9.cicely.de>, Bernd Walter writes:

>I need a realtime behavour in the (-current) kernel with 1ms
>resolution and a presision of 500us.

You are in trouble.

>I thought about these two ways:
>- use timeout(9), but it seems that on i386 we only have a
>  resolution of 10ms.
>  And I don't know of what presision quality I can expect.
>  Can the resolution changed to 1ms as we have on alpha?

You can change this by changing the "hz" of the kernel.

I belive this can be done from either the loader or the kernel
config file.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.