From owner-freebsd-current@FreeBSD.ORG  Thu Aug 23 14:35:19 2012
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: current@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 814DB1065673
	for <current@freebsd.org>; Thu, 23 Aug 2012 14:35:19 +0000 (UTC)
	(envelope-from luigi@onelab2.iet.unipi.it)
Received: from onelab2.iet.unipi.it (onelab2.iet.unipi.it [131.114.59.238])
	by mx1.freebsd.org (Postfix) with ESMTP id 472568FC1B
	for <current@freebsd.org>; Thu, 23 Aug 2012 14:35:17 +0000 (UTC)
Received: by onelab2.iet.unipi.it (Postfix, from userid 275)
	id E4ECB7300A; Thu, 23 Aug 2012 16:54:20 +0200 (CEST)
Date: Thu, 23 Aug 2012 16:54:20 +0200
From: Luigi Rizzo <rizzo@iet.unipi.it>
To: current@freebsd.org
Message-ID: <20120823145420.GB3103@onelab2.iet.unipi.it>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.4.2.3i
Cc: 
Subject: TUNABLE_INT vs TUNABLE_INT_FETCH
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 23 Aug 2012 14:35:19 -0000

Hi,
I am a bit unclear on what are the pros and cons of using
TUNABLE_INT vs TUNABLE_INT_FETCH within a device driver.

As a matter of fact, as i read the definitions in sys/kernel.h
I almost wonder whether we need the TUNABLE_INT form at all.

can anyone help clarify the differences ?

thanks
luigi