From owner-freebsd-arch@FreeBSD.ORG Wed Aug 10 21:14:10 2005 Return-Path: X-Original-To: freebsd-arch@freebsd.org Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BEDCF16A41F; Wed, 10 Aug 2005 21:14:10 +0000 (GMT) (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 3944743D48; Wed, 10 Aug 2005 21:14:07 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from [192.168.254.14] (imini.samsco.home [192.168.254.14]) (authenticated bits=0) by pooker.samsco.org (8.13.3/8.13.3) with ESMTP id j7ALPv4c010990; Wed, 10 Aug 2005 15:25:57 -0600 (MDT) (envelope-from scottl@samsco.org) Message-ID: <42FA6E0E.4070205@samsco.org> Date: Wed, 10 Aug 2005 15:13:50 -0600 From: Scott Long User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.7.7) Gecko/20050416 X-Accept-Language: en-us, en MIME-Version: 1.0 To: John Baldwin References: <42F9ECF2.8080809@freebsd.org> <200508100911.50004.jhb@FreeBSD.org> <1123704605.54957.8.camel@realtime.exit.com> <200508101638.27087.jhb@FreeBSD.org> In-Reply-To: <200508101638.27087.jhb@FreeBSD.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.8 required=3.8 tests=ALL_TRUSTED autolearn=failed version=3.0.2 X-Spam-Checker-Version: SpamAssassin 3.0.2 (2004-11-16) on pooker.samsco.org X-Mailman-Approved-At: Thu, 11 Aug 2005 11:43:39 +0000 Cc: frank@exit.com, Andre Oppermann , freebsd-arch@freebsd.org Subject: Re: Special schedulers, one CPU only kernel, one only userland X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Aug 2005 21:14:10 -0000 John Baldwin wrote: > On Wednesday 10 August 2005 04:10 pm, Frank Mayhar wrote: > >>On Wed, 2005-08-10 at 09:11 -0400, John Baldwin wrote: >> >>>I think this is the model that BSD/OS employed >>>for SMP in its 4.x series before they did their version of SMPng. >> >>I didn't grunge around in the scheduler (much), but as far as I'm aware >>BSD/OS 4.x used the Big Giant Lock mechanism just as FreeBSD did, and >>for the same reason. > > > I believe that at some point during the 4.x series they added a scheduler lock > that covered just enough to allow threads that weren't asleep in the kernel > to be switched to without require the big giant lock and that it was a pretty > decent performance win over the earlier single BGL ala FreeBSD 4.x. > So when a syscall is made on an AP, does it get serviced on the same AP (assuming that the lock is available and no sleeping is needed), or does it get serviced my the BSP? Where kernel threads explicitely pinned to the BSP? Was the APIC explicitely programmed to deliver only to the BSP? Scott