From owner-freebsd-hackers@FreeBSD.ORG  Thu Jun  9 13:32:25 2005
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
X-Original-To: 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 AE03716A41C
	for <hackers@freebsd.org>; Thu,  9 Jun 2005 13:32:25 +0000 (GMT)
	(envelope-from jhb@FreeBSD.org)
Received: from s-utl01-sjpop.stsn.net (s-utl01-sjpop.stsn.net [72.254.0.17])
	by mx1.FreeBSD.org (Postfix) with SMTP id 846EE43D1F
	for <hackers@freebsd.org>; Thu,  9 Jun 2005 13:32:25 +0000 (GMT)
	(envelope-from jhb@FreeBSD.org)
Received: from s-utl01-sjpop.stsn.net ([127.0.0.1])
	by s-utl01-sjpop.stsn.net (SMSSMTP 4.0.0.59) with SMTP id
	M2005060906322524175 ; Thu, 09 Jun 2005 06:32:25 -0700
Received: from [10.0.1.5] ([10.1.191.21]) by s-utl01-sjpop.stsn.net;
	Thu, 9 Jun 2005 06:32:22 -0700
In-Reply-To: <20050520224928.GI2129@cirb503493.alcatel.com.au>
References: <200505201340.36176.hselasky@c2i.net> <428E12B0.9020208@samsco.org>
	<20050520173236.GG1201@green.homeunix.org>
	<200505202151.35831.hselasky@c2i.net>
	<20050520224928.GI2129@cirb503493.alcatel.com.au>
Mime-Version: 1.0 (Apple Message framework v622)
Content-Type: text/plain; charset=US-ASCII; format=flowed
Message-Id: <1bc2efb62d58b3be72efe326781aee70@FreeBSD.org>
Content-Transfer-Encoding: 7bit
From: John Baldwin <jhb@FreeBSD.org>
Date: Thu, 9 Jun 2005 06:31:13 -0700
To: Peter Jeremy <PeterJeremy@optushome.com.au>
X-Mailer: Apple Mail (2.622)
Cc: hackers@freebsd.org, Hans Petter Selasky <hselasky@c2i.net>
Subject: Re: problems with new the "contigmalloc" routine
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
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: Thu, 09 Jun 2005 13:32:25 -0000


On May 20, 2005, at 3:49 PM, Peter Jeremy wrote:
> On Fri, 2005-May-20 21:51:34 +0200, Hans Petter Selasky wrote:
>> Can anyone explain why "uiomove()" has to sleep, and why there is no
>> non-blocking "uiomove()"?
>
> As far as I can see, uiomove() only sleeps if it is asked to do a
> kernel<->userland move that takes more than twice a scheduler quantum.
> As long as you don't uiomove() ridiculous amounts of data, it should
> never sleep.

It can also sleep if it is reading from or writing to user memory if 
any of that memory needs to be faulted in.

-- 
John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org