From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: [RFC PATCH 1/3] xl: replace vcpu-set --ignore-host with --ignore-warn Date: Tue, 23 Jul 2013 00:29:36 +0100 Message-ID: <51EDC060.6040608@eu.citrix.com> References: <1374248938-11232-1-git-send-email-konrad.wilk@oracle.com> <1374248938-11232-2-git-send-email-konrad.wilk@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1374248938-11232-2-git-send-email-konrad.wilk@oracle.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Konrad Rzeszutek Wilk Cc: xen-devel@lists.xensource.com, ian.jackson@eu.citrix.com, Ian.Campbell@citrix.com List-Id: xen-devel@lists.xenproject.org On 07/19/2013 04:48 PM, Konrad Rzeszutek Wilk wrote: > When Xen 4.3 was released we had a discussion whether we should > allow the vcpu-set command to allow the user to set more than > physical CPUs for a guest. The author brought up: > - Xend used to do it, > - If a user wants to do it, let them do it, > - The original author of the change did not realize the > side-effect his patch caused this and had no intention of changing it. > - The user can already boot a massively overcommitted guest by > having a large 'vcpus=' value in the guest config and we allow > that. > > Since we were close to the release we added --ignore-host parameter > as a mechanism for a user to still set more vCPUs that the physical > machine as a stop-gate. > > This patch removes said option and adds the --ignore-warn option. > By default the user is allowed to set as many vCPUs as they would like. > We will print out a warning if the value is higher than the physical > CPU count. The --ignore-warn will silence said warning. I think this is a good change in general, but I don't think the name is quite right. You're not ignoring the warnings, you're turning them off. Maybe make the function argument "warn", and the option "--no-warn"? > + host_cpu = libxl_get_max_cpus(ctx); > + if (max_vcpus > host_cpu && !ignore_warn) { > + fprintf(stderr, "WARNING: You are overcommmitting! You have %d" \ > + " physical CPUs and want %d vCPUs! Continuing, use" \ > + " --ignore-warn to silence this.\n", host_cpu, max_vcpus); > } This is relatively minor, but you might as well keep the same basic structure here, and only call libxl_get_max_cpus() if warn is set. -George