Date: Wed, 28 Nov 2018 14:35:27 +0000 From: Simon Connah <scopensource@gmail.com> To: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net> Cc: "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org> Subject: Re: Any plans to increase the maximum number of virtual CPUs above 16? Message-ID: <023c89a6-12fa-69e4-5421-50a942488d7a@gmail.com> In-Reply-To: <201811272306.wARN6dKU003727@pdx.rh.CN85.dnsmgr.net> References: <201811272306.wARN6dKU003727@pdx.rh.CN85.dnsmgr.net>
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On 27/11/2018 23:06, Rodney W. Grimes wrote: >> I was reading the bhyve man page and noticed that it said the maximum >> number of virtual CPUs is limited to 16. With AMD Epyc being out with 32 >> cores and 64 threads per CPU and being able to have 2 of them in one >> system this number seems rather low by modern standards. > > So you can run 4 x 16 vcpu VM's, probably more common than > someone trying to run 1 VM of 32 or 64 vcpu. > >> >> Are there any plans to increase this number to something like 32 virtual >> CPUs? > > There is work in process to change this from a compile time > kernel constant to a per VM value set using the undocumnted, > but present value in the cpu_topology option max_cpu. > > We do not want to just crank this value up as data structures > for each VM are sized on the MAXCPU connstant, and doubling > that to 32 would be fairly wasteful for low core count VM's. > Thank you for the reply. Ah, that makes sense. Nice to know that it is something that is being worked on. The only reason I really want to go above 16 vCPUs is that some other providers offer VPS instances with more vCPUs than that. I could quite happily live with 16 myself.
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