From owner-freebsd-arch@FreeBSD.ORG  Fri Jan  4 10:40:46 2008
Return-Path: <owner-freebsd-arch@FreeBSD.ORG>
Delivered-To: arch@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 77AAE16A421;
	Fri,  4 Jan 2008 10:40:46 +0000 (UTC)
	(envelope-from phk@critter.freebsd.dk)
Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222])
	by mx1.freebsd.org (Postfix) with ESMTP id 2BFA913C469;
	Fri,  4 Jan 2008 10:40:46 +0000 (UTC)
	(envelope-from phk@critter.freebsd.dk)
Received: from critter.freebsd.dk (unknown [192.168.61.3])
	by phk.freebsd.dk (Postfix) with ESMTP id 2141D17105;
	Fri,  4 Jan 2008 10:40:45 +0000 (UTC)
Received: from critter.freebsd.dk (localhost [127.0.0.1])
	by critter.freebsd.dk (8.14.2/8.14.2) with ESMTP id m04Aeil4005078;
	Fri, 4 Jan 2008 10:40:44 GMT (envelope-from phk@critter.freebsd.dk)
To: "Attilio Rao" <attilio@freebsd.org>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Thu, 03 Jan 2008 16:48:37 +0100."
	<3bbf2fe10801030748u28fe346byd051cecfa55cf636@mail.gmail.com> 
Date: Fri, 04 Jan 2008 10:40:44 +0000
Message-ID: <5077.1199443244@critter.freebsd.dk>
Sender: phk@critter.freebsd.dk
Cc: arch@freebsd.org, Robert Watson <rwatson@freebsd.org>,
	Andre Oppermann <andre@freebsd.org>, freebsd-arch@freebsd.org
Subject: Re: New "timeout" api, to replace callout 
X-BeenThere: freebsd-arch@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussion related to FreeBSD architecture <freebsd-arch.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-arch>
List-Post: <mailto:freebsd-arch@freebsd.org>
List-Help: <mailto:freebsd-arch-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 04 Jan 2008 10:40:46 -0000

In message <3bbf2fe10801030748u28fe346byd051cecfa55cf636@mail.gmail.com>, "Atti
lio Rao" writes:
>2008/1/3, Poul-Henning Kamp <phk@phk.freebsd.dk>:

>> What I'm proposing is that your thread will sleep on a plain, but
>> unrelated mutex (internal to the timeout code) until the function
>> comes back.
>>
>> Based on your description above, you won't be able to tell the
>> any difference between this and what you wish for.
>
>This will be hardly feasible.
>Internal callout subsystem locks probabilly need to be spinlocks in
>order to avoid lock mismatches against sleepable locks.

callouts will not be allowed to sleep, they never should have been
able to.

-- 
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.