From owner-freebsd-hackers@FreeBSD.ORG Thu Nov 25 15:28:51 2010 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B6276106566B; Thu, 25 Nov 2010 15:28:51 +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 87F7D8FC0C; Thu, 25 Nov 2010 15:28:51 +0000 (UTC) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id 4AFA746B2E; Thu, 25 Nov 2010 10:28:51 -0500 (EST) Received: from John-Baldwins-Macbook-Pro.local (d-69-161-103-3.cpe.metrocast.net [69.161.103.3]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 5CE818A009; Thu, 25 Nov 2010 10:28:50 -0500 (EST) Message-ID: <4CEE80B1.6000602@FreeBSD.org> Date: Thu, 25 Nov 2010 10:28:49 -0500 From: John Baldwin User-Agent: Thunderbird 2.0.0.24 (Macintosh/20100228) MIME-Version: 1.0 To: Andriy Gapon References: <201011220924.53709.jhb@freebsd.org> <4CEBDD42.5010007@freebsd.org> In-Reply-To: <4CEBDD42.5010007@freebsd.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.6 (bigwig.baldwin.cx); Thu, 25 Nov 2010 10:28:50 -0500 (EST) X-Virus-Scanned: clamav-milter 0.96.3 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-0.9 required=4.2 tests=BAYES_00,RDNS_DYNAMIC autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on bigwig.baldwin.cx Cc: Garrett Cooper , freebsd-hackers@freebsd.org Subject: Re: Best way to determine if an IRQ is present X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 25 Nov 2010 15:28:51 -0000 Andriy Gapon wrote: > on 22/11/2010 16:24 John Baldwin said the following: >> Well, the real solution is actually larger than described in the PR. What you >> really want to do is take the logical CPUs offline when they are "halted". >> Taking a CPU offline should trigger an EVENTHANDLER that various bits of code >> could invoke. In the case of platforms that support binding interrupts to >> CPUs (x86 and sparc64 at least), they would install an event handler that >> searches the MD interrupt tables (e.g. the interrupt_sources[] array on x86) >> and move bound interrupts to other CPUs. However, I think all the interrupt >> bits will be MD, not MI. > > That's a good idea and a comprehensive approach. > One minor technical detail - should an offlined CPU be removed from all_cpus mask/set? That's tricky. In other e-mails I've had on this topic, the idea has been to have a new online_cpus mask and maybe a CPU_ONLINE() test macro similar to CPU_ABSENT(). In that case, an offline CPU should still be in all_cpus, but many places that use all_cpus would need to use online_cpus instead. -- John Baldwin