From owner-freebsd-smp Mon Dec 7 14:20:44 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id OAA24287 for freebsd-smp-outgoing; Mon, 7 Dec 1998 14:20:44 -0800 (PST) (envelope-from owner-freebsd-smp@FreeBSD.ORG) Received: from smtp04.primenet.com (smtp04.primenet.com [206.165.6.134]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id OAA24275 for ; Mon, 7 Dec 1998 14:20:41 -0800 (PST) (envelope-from tlambert@usr06.primenet.com) Received: (from daemon@localhost) by smtp04.primenet.com (8.8.8/8.8.8) id PAA22338; Mon, 7 Dec 1998 15:20:33 -0700 (MST) Received: from usr06.primenet.com(206.165.6.206) via SMTP by smtp04.primenet.com, id smtpd022094; Mon Dec 7 15:20:21 1998 Received: (from tlambert@localhost) by usr06.primenet.com (8.8.5/8.8.5) id PAA16916; Mon, 7 Dec 1998 15:19:58 -0700 (MST) From: Terry Lambert Message-Id: <199812072219.PAA16916@usr06.primenet.com> Subject: Re: Pthreads and SMP To: marcelk@stack.nl (Marcel van Kervinck) Date: Mon, 7 Dec 1998 22:19:57 +0000 (GMT) Cc: smp@FreeBSD.ORG In-Reply-To: <19981206172549.A11335@unox.student.tue.nl> from "Marcel van Kervinck" at Dec 6, 98 05:25:49 pm X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > Perhaps I've missed something obvious But: it seems to me that a process > that uses multiple threads doesn't spread them over more processors? That is correct. The threads are user space threads, which execute in a single process context. > I tried on a dual PII, running fbsd 3.0, and a program that simply did > a few pthread_create() calls. There are L1 and L2 cache coherency issues that impact bus based arbitration and invalidation bottlenecks, there are scheduler issues (both user and kernel space), there are stack issues, there are address space issues, memory model issues, and a slew more issues. These problems are not as trivially solvable, as the poor Linux and SVR4 kernel threading implementations, or the EGCS thread support assumptions would have you believe. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message