From owner-freebsd-current@FreeBSD.ORG Sun Oct 29 16:24:20 2006 Return-Path: X-Original-To: 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 9085716A40F; Sun, 29 Oct 2006 16:24:20 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id A39BB43D55; Sun, 29 Oct 2006 16:24:15 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from [192.168.254.11] (phobos.samsco.home [192.168.254.11]) (authenticated bits=0) by pooker.samsco.org (8.13.4/8.13.4) with ESMTP id k9TGO7EJ030966; Sun, 29 Oct 2006 09:24:14 -0700 (MST) (envelope-from scottl@samsco.org) Message-ID: <4544D5A7.8070604@samsco.org> Date: Sun, 29 Oct 2006 09:24:07 -0700 From: Scott Long User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.0.7) Gecko/20060910 SeaMonkey/1.0.5 MIME-Version: 1.0 To: Robert Watson References: <45425D92.8060205@elischer.org> <20061028194125.GL30707@riyal.ugcs.caltech.edu> <200610291257.11744.Lucas.James@ldjcs.com.au> <20061029090945.P27107@fledge.watson.org> In-Reply-To: <20061029090945.P27107@fledge.watson.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-1.4 required=3.8 tests=ALL_TRUSTED autolearn=failed version=3.1.1 X-Spam-Checker-Version: SpamAssassin 3.1.1 (2006-03-10) on pooker.samsco.org Cc: Lucas James , freebsd-current@freebsd.org Subject: Re: Comments on the KSE option X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 29 Oct 2006 16:24:20 -0000 Robert Watson wrote: > > On Sun, 29 Oct 2006, Lucas James wrote: > >> I read what Paul said was that system scope threads have a different >> "fairness" than processes. ie: >> >> If your application requires 1000 threads of execution, you can write >> it three ways, with 1000 processes, 1000 system scope threads or 1000 >> process scope threads (or a mix of the three). >> >> This whole "fairness" argument is about making system scope threads >> have the same priority as process scope threads. It leaves out the >> process model. >> >> The real question here is: are we going to make system scope thread >> model fair compared to process scope threaded model, or fair compared >> to the separate processes model? >> >> Yes, the process scope threads are allways going to be the poor man >> with regard to priority, but as the kernel doesn't see the threads you >> can't do much about it. > > I think there are at least two core questions being discussed here: > > (1) Does the "fairness" model currently implemented in the KSE code mean > well, > but cause significant performance problems in practice for real-world > applications? > > (2) Are the cost and complexity impacts of KSE in kernel architecture > outweighed by the flexibility and performance benefits of M:N > threading? > > Now is definitely the time for us to be discussing, measuring, > experimenting, etc, because addressing the issues of higher concurrency > for 7.0 will depend on having decided on a strategy for our scheduler. > I'd like to add (3) Who is committed to maintaining and improving the M:N and KSE architectures for the long term? THR and 1:1 has an active and committed maintainer right now, KSE does not. Whether KSE is 'better' is purely academic if no one is willing to actually make it work. Scott