From owner-freebsd-hackers Sun Dec 5 18:20:32 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from ind.alcatel.com (postal.xylan.com [208.8.0.248]) by hub.freebsd.org (Postfix) with ESMTP id 0C19C14EE0 for ; Sun, 5 Dec 1999 18:20:09 -0800 (PST) (envelope-from wes@softweyr.com) Received: from mailhub.xylan.com (mailhub [198.206.181.70]) by ind.alcatel.com (8.9.3+Sun/8.9.1 (ind.alcatel.com 3.0 [OUT])) with SMTP id SAA15209; Sun, 5 Dec 1999 18:19:02 -0800 (PST) X-Origination-Site: Received: from omni.xylan.com by mailhub.xylan.com (SMI-8.6/SMI-SVR4 (mailhub 2.1 [HUB])) id SAA24310; Sun, 5 Dec 1999 18:19:02 -0800 Received: from softweyr.com ([204.68.178.39]) by omni.xylan.com (4.1/SMI-4.1 (xylan engr [SPOOL])) id AA22264; Sun, 5 Dec 99 18:18:51 PST Message-Id: <384B1D25.DFAF198E@softweyr.com> Date: Sun, 05 Dec 1999 19:19:17 -0700 From: Wes Peters Organization: Softweyr LLC X-Mailer: Mozilla 4.61 [en] (X11; I; FreeBSD 3.3-RELEASE i386) X-Accept-Language: en Mime-Version: 1.0 To: Nick Hibma Cc: Doug Barton , freebsd-hackers@FreeBSD.ORG Subject: Re: Basic question about threads and SMP References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Nick Hibma wrote: > > Being multi-threaded has almost nothing to do with being > multi-processor. Multi-threading means that your application has > multiple threads of execution that are able to run simultaneously. > > The multi-processing capability of your box means that 2 threads of > execution, be it a process or a thread within a process, are executed > _literally_ at the same time, and not in simulated concurrency like it > happens on a UP box. Note that this happens ONLY if both threads of execution are processor mobile. If your system supports user-space threads as part of a process and the process can't be split across CPUs, you might as well have a UP system. (Except everything else can run on the other processor, so SMP is still a small win.) This is the situation with threads and SMP in -current. -- "Where am I, and what am I doing in this handbasket?" Wes Peters Softweyr LLC wes@softweyr.com http://softweyr.com/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message