From owner-freebsd-arm@freebsd.org Wed Jan 13 15:21:40 2021 Return-Path: Delivered-To: freebsd-arm@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 6EB1E4E0274; Wed, 13 Jan 2021 15:21:40 +0000 (UTC) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (br1.CN84in.dnsmgr.net [69.59.192.140]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4DGB4M2pX4z4pJF; Wed, 13 Jan 2021 15:21:39 +0000 (UTC) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (localhost [127.0.0.1]) by gndrsh.dnsmgr.net (8.13.3/8.13.3) with ESMTP id 10DFLbDq041912; Wed, 13 Jan 2021 07:21:37 -0800 (PST) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Received: (from freebsd-rwg@localhost) by gndrsh.dnsmgr.net (8.13.3/8.13.3/Submit) id 10DFLbPj041911; Wed, 13 Jan 2021 07:21:37 -0800 (PST) (envelope-from freebsd-rwg) From: "Rodney W. Grimes" Message-Id: <202101131521.10DFLbPj041911@gndrsh.dnsmgr.net> Subject: Re: [bhyve][arm64] Number of allowed vcpus In-Reply-To: To: Mihai Carabas Date: Wed, 13 Jan 2021 07:21:37 -0800 (PST) CC: "Rodney W. 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List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 13 Jan 2021 15:21:40 -0000 > On Wed, Jan 13, 2021 at 4:55 PM Rodney W. Grimes < > freebsd-rwg@gndrsh.dnsmgr.net> wrote: > > > > Hello, > > > > > > >From my perspective bhyve should use what is stated in the device tree > > if > > > no parameter is given and throw an error when N is greater than the > > device > > > tree value. > > > > > > Mihai > > > > That seems to be one reasonable solution. I am not very informed on what > > the CPU over commit situation is on an ARM cpu with respect to > > virtualization. > > > > I would also propose as an alternative to just do what was asked by the > > user, which is the current amd64 implementation, OR do as asked and > > emmit a warning message. > > > > I would ask given what was said above: isnt this the same situation as > > if the sum of all VM VCPU's is more than the total cores in the system? > > That is a very common situation, and one we must not restrict. > > > > We are talking here about the device tree of the guest. If you boot up a > guest with a device tree of X vcpus, why specify something else on the > command line? Oh, that is/was not clear from the original post, it did not specify which device tree was being discussed. How do we even see the guest device tree (again, pointing to my lack of knowledge on the ARM bhyve implementation.) Also would this not be about the same as taking my flash card out of a 4 CPU system and plugging it into a 8 CPU system without updating the device tree? What would real hardware do here? > > > On Wed, Jan 13, 2021 at 1:55 PM Andrei Martin < > > andrei.cos.martin@gmail.com> > > > wrote: > > > > > > > Hello, > > > > > > > > While working on enabling multiple virtual cpus for the arm64 virtual > > > > machine > > > > I used the bhyve's "-c N" parameter to create N cpus (it gets only the > > > > cpus, in contrast to the amd64). If N is smaller than the number of > > cores > > > > described in the device tree it will enable only N and if it's larger > > it > > > > will enable only the number of cores from the device tree. > > > > > > > > I don't know if it is the best approach. Another way would be to enable > > > > all the cpus from the device tree, no more, no less. > > > > > > > > Do you have any suggestions? > > > > > > > > Andrei > > > > > > > _______________________________________________ > > > freebsd-virtualization@freebsd.org mailing list > > > https://lists.freebsd.org/mailman/listinfo/freebsd-virtualization > > > To unsubscribe, send any mail to " > > freebsd-virtualization-unsubscribe@freebsd.org" > > > > > > > -- > > Rod Grimes > > rgrimes@freebsd.org > > -- Rod Grimes rgrimes@freebsd.org