From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: Date: Mon, 21 Apr 2014 18:49:34 -0300 Message-ID: <20140421214934.GA6414@amt.cnet> References: <20140416211734.GA15155@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm To: Marcus White Return-path: Received: from mx1.redhat.com ([209.132.183.28]:45477 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755042AbaDUVtt (ORCPT ); Mon, 21 Apr 2014 17:49:49 -0400 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Apr 17, 2014 at 02:33:41PM -0700, Marcus White wrote: > >> > Hello, > >> > I had some basic questions regarding KVM, and would appreciate any help:) > >> > > >> > I have been reading about the KVM architecture, and as I understand > >> > it, the guest shows up as a regular process in the host itself.. > >> > > >> > I had some questions around that.. > >> > > >> > 1. Are the guest processes implemented as a control group within the > >> > overall VM process itself? Is the VM a kernel process or a user > >> > process? > > > > User process. > > > >> > 2. Is there a way for me to force some specific CPU/s to a guest, and > >> > those CPUs to be not used for any work on the host itself? Pinning is > >> > just making sure the vCPU runs on the same physical CPU always, I am > >> > looking for something more than that.. > > > > Control groups. > Do control groups prevent the host from using those CPUs? I want only > the VM to use the CPUs, and dont want any host user or kernel threads > to run on that physical CPU. I looked up control groups, maybe I > missed something there. I will go back and take a look. If you can > clarify, I would appreciate it:) Per-CPU kernel threads usually perform necessary work on behalf of the CPU. For other user threads, yes you can have them execute exclusively on other processors. > >> > 3. If the host is compiled as a non pre-emptible kernel, kernel > >> > process run to completion until they give up the CPU themselves. In > >> > the context of a guest, I am trying to understand what that would mean > >> > in the context of KVM and guest VMs. If the VM is a user process, it > >> > means nothing, I wasnt sure as per (1). > > > > What problem are you trying to solve? > Its more of an investigation at this point to understand what can happen.. http://www.phoronix.com/scan.php?page=news_item&px=MTI1NTg http://www.linuxplumbersconf.org/2013/ocw/sessions/1143