From owner-svn-src-head@FreeBSD.ORG Wed Apr 22 21:59:27 2009 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D64391065672; Wed, 22 Apr 2009 21:59:27 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id A90E18FC21; Wed, 22 Apr 2009 21:59:27 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id 4A1CB46B06; Wed, 22 Apr 2009 17:59:27 -0400 (EDT) Received: from jhbbsd.hudson-trading.com (unknown [209.249.190.8]) by bigwig.baldwin.cx (Postfix) with ESMTPA id 18C768A01A; Wed, 22 Apr 2009 17:59:26 -0400 (EDT) From: John Baldwin To: src-committers@freebsd.org Date: Wed, 22 Apr 2009 17:59:04 -0400 User-Agent: KMail/1.9.7 References: <200904222140.n3MLebn3068260@svn.freebsd.org> In-Reply-To: <200904222140.n3MLebn3068260@svn.freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200904221759.04446.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.0.1 (bigwig.baldwin.cx); Wed, 22 Apr 2009 17:59:26 -0400 (EDT) X-Virus-Scanned: clamav-milter 0.95 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=0.1 required=4.2 tests=AWL,RDNS_NONE autolearn=no version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on bigwig.baldwin.cx Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org Subject: Re: svn commit: r191405 - in head/sys: amd64/amd64 i386/i386 X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Apr 2009 21:59:28 -0000 On Wednesday 22 April 2009 5:40:37 pm John Baldwin wrote: > Author: jhb > Date: Wed Apr 22 21:40:37 2009 > New Revision: 191405 > URL: http://svn.freebsd.org/changeset/base/191405 > > Log: > Adjust the way we number CPUs on x86 so that we attempt to "group" all > logical CPUs in a package. We do this by numbering the non-boot CPUs > by starting with the first CPU whose APIC ID is after the boot CPU and > wrapping back around to APIC ID 0 if needed rather than always starting > at APIC ID 0. While here, adjust the cpu_mp_announce() routine to list > CPUs based on the mapping established by assign_cpu_ids() rather than > making assumptions about the algorithm assign_cpu_ids() uses. An example is probably in order for this to make sense. Suppose you have a system with two quad-core CPUs. Package 0 has CPUs numbered 0, 1, 2, and 3. Package 1 has CPUs numbered 4, 5, 6, and 7. With the old code, if package 0 won the election to be the boot processor, then CPU 0 would be the BSP and the logical IDs would match the APIC IDs. However, if package 1 won the election during POST, then CPU 0 would be APIC ID 4 on package 0 followed by CPU 1 being APIC ID 0, CPU 2 being APIC ID 1, etc. Thus, when CPU 0 was the boot CPU you had a nice grouping where CPUs 0-3 were a single package and CPUs 4-7 were another package. However, when CPU 4 was the boot CPU, CPUs 0 and 5-7 where one package, and CPUs 1-4 where the second package. The effect of this patch is to change the case when CPU 4 is the boot CPU such that CPUs 0-3 are now all from CPU 4's package (APIC IDs 4-7), and CPUs 4-7 are from the other package (APIC IDs 0-3). What this means, in turn, is that in both cases you now always have CPUs 0-3 as one package and CPUs 4-7 as another package regardless of which CPU wins the boot-time election. -- John Baldwin