From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:56198) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UTGkh-0006E1-Gl for qemu-devel@nongnu.org; Fri, 19 Apr 2013 15:13:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UTGkg-0004Na-6i for qemu-devel@nongnu.org; Fri, 19 Apr 2013 15:13:43 -0400 Received: from e06smtp12.uk.ibm.com ([195.75.94.108]:59882) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UTGkf-0004Mi-Tc for qemu-devel@nongnu.org; Fri, 19 Apr 2013 15:13:42 -0400 Received: from /spool/local by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 19 Apr 2013 20:10:19 +0100 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp01.portsmouth.uk.ibm.com (Postfix) with ESMTP id 53B4D17D8017 for ; Fri, 19 Apr 2013 20:14:31 +0100 (BST) Received: from d06av02.portsmouth.uk.ibm.com (d06av02.portsmouth.uk.ibm.com [9.149.37.228]) by b06cxnps4076.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r3JJDPau44236840 for ; Fri, 19 Apr 2013 19:13:25 GMT Received: from d06av02.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av02.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r3JJDXpJ028981 for ; Fri, 19 Apr 2013 13:13:34 -0600 Message-ID: <5171975C.2000608@de.ibm.com> Date: Fri, 19 Apr 2013 21:13:32 +0200 From: Christian Borntraeger MIME-Version: 1.0 References: <1364971345-3110-1-git-send-email-jfrei@linux.vnet.ibm.com> <516EE4AD.3090508@suse.de> <20130419075158.GC14662@linux.vnet.ibm.com> <517143B4.2060109@suse.de> In-Reply-To: <517143B4.2060109@suse.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [RFC/PATCH 0/1] cpu hotplug for s390 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?ISO-8859-1?Q?Andreas_F=E4rber?= Cc: Eduardo Habkost , qemu-devel , Alexander Graf , Jens Freimann , Cornelia Huck , Igor Mammedov On 19/04/13 15:16, Andreas Färber wrote: [...] >>> Background is that for x86 we currently have a flat CPU core/thread >>> namespace but would need to deal with sockets, cores and threads to get >>> topologies right. I assume there are no such issues on s390x, so that >>> the vCPU to CPUState mapping could stay 1:1? >> >> s390 hardware today already has a topology and CPU features. We are not >> modelling it in QEMU right now, but want to go there in the future so that >> there would be no simple 1:1 mapping anymore. > > In that case please enlighten us how the topology model should/could > look like in the future, so that we can align this with the x86 > remodelling and APIC/ID discussion. Current models provide topology information via the STSI instruction (http://publibfi.boulder.ibm.com/epubs/pdf/dz9zr009.pdf see page 10-134 and following) function code 15. The system basically informs about cpus and containers, which boils down to how the hardware is organized: e.g. fr zec12 we have up to 4 Nodes(aka books). A book contains one MCM with 6 processors. Each processor then has 6 cores. (see http://publibfi.boulder.ibm.com/epubs/pdf/dz9zr009.pdf) Future systems might look different, I dont know if and how the topology will change. Currently there is no information about memory locality, only processor grouping. As Jens said, as of now we do not provide any topology information to the guest, but we might to change that in the future. I havent followed the x86 discussion, so please let me know if that doesnt answer your question. Christian