From owner-freebsd-current@FreeBSD.ORG  Wed Apr  2 15:39:39 2003
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 6074E37B401
	for <current@freebsd.org>; Wed,  2 Apr 2003 15:39:39 -0800 (PST)
Received: from mail.chesapeake.net (chesapeake.net [205.130.220.14])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 96E0943F75
	for <current@freebsd.org>; Wed,  2 Apr 2003 15:39:38 -0800 (PST)
	(envelope-from jroberson@chesapeake.net)
Received: from localhost (jroberson@localhost)
	by mail.chesapeake.net (8.11.6/8.11.6) with ESMTP id h32NdYL88952;
	Wed, 2 Apr 2003 18:39:34 -0500 (EST)
	(envelope-from jroberson@chesapeake.net)
Date: Wed, 2 Apr 2003 18:39:33 -0500 (EST)
From: Jeff Roberson <jroberson@chesapeake.net>
To: Terry Lambert <tlambert2@mindspring.com>
In-Reply-To: <3E8B72C2.343AAEBD@mindspring.com>
Message-ID: <20030402183406.O64602-100000@mail.chesapeake.net>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
cc: csujun@21cn.com
cc: current@freebsd.org
Subject: Re: libthr and 1:1 threading.
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.1
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: Wed, 02 Apr 2003 23:39:39 -0000


On Wed, 2 Apr 2003, Terry Lambert wrote:

> Peter Wemm wrote:
> > No.  It gives the ability for a thread to block on a syscall without
> > stalling the entire system.  Just try using mysqld on a system using libc_r
> > and heavy disk IO.  You can't select() on a read() from disk.  Thats the
> > ultimate reason to do it.  The SMP parallelism is a bonus.
>
> Bug in FreeBSD's NBIO implementation.  A read() that would result
> in page-in needs to queue the request, but return EAGAIN to user
> space to indicate the request cannot be satisfied.  Making select()
> come true for disk I/O after the fault is satisfied is a seperate
> issue.  Probably need to pass the fd all the way down.
>

Please quote the standard that defines this behavior.  This is entirely
counter to everything that I have ever read on the subject.