From owner-freebsd-current@FreeBSD.ORG  Tue Mar 17 14:04:26 2009
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 5FEC91065672
	for <current@freebsd.org>; Tue, 17 Mar 2009 14:04:26 +0000 (UTC)
	(envelope-from rwatson@FreeBSD.org)
Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42])
	by mx1.freebsd.org (Postfix) with ESMTP id 3BBF38FC1A
	for <current@freebsd.org>; Tue, 17 Mar 2009 14:04:26 +0000 (UTC)
	(envelope-from rwatson@FreeBSD.org)
Received: from fledge.watson.org (fledge.watson.org [65.122.17.41])
	by cyrus.watson.org (Postfix) with ESMTPS id D0AAA46B5B;
	Tue, 17 Mar 2009 10:04:25 -0400 (EDT)
Date: Tue, 17 Mar 2009 14:04:25 +0000 (GMT)
From: Robert Watson <rwatson@FreeBSD.org>
X-X-Sender: robert@fledge.watson.org
To: Barney Cordoba <barney_cordoba@yahoo.com>
In-Reply-To: <929422.83072.qm@web63908.mail.re1.yahoo.com>
Message-ID: <alpine.BSF.2.00.0903171359590.55043@fledge.watson.org>
References: <929422.83072.qm@web63908.mail.re1.yahoo.com>
User-Agent: Alpine 2.00 (BSF 1167 2008-08-23)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
Cc: current@freebsd.org
Subject: Re: Interrupt routine usage not shown by top in 8.0
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: Tue, 17 Mar 2009 14:04:26 -0000


On Fri, 13 Mar 2009, Barney Cordoba wrote:

> Can you clarify the difference between using a fast irq and then launching a 
> thread (as em does) versus using an MPSAFE interrupt as most other drivers 
> (particularly bge and ibg) use?
>
> How do they differ in terms of how they are called and executed?

I agree that the code there looks inconsistent in when it uses fast vs regular 
mpsafe interrupts, Scott may be able to shed more light on this.  I'm 
especially confused by:

#if __FreeBSD_version < 700000
         if ((error = bus_setup_intr(dev, adapter->res[0],
             INTR_TYPE_NET | INTR_FAST, em_irq_fast, adapter,
#else
         if ((error = bus_setup_intr(dev, adapter->res[0],
             INTR_TYPE_NET, em_irq_fast, NULL, adapter,
#endif

This is in what I took to be the INTR_FAST registration, so I would expect 
also to see INTR_FAST in the mask for that second bit.

Robert N M Watson
Computer Laboratory
University of Cambridge