From: "Doug Bissett" <virtualized_ecs_users@2rosenthals.com> Subject: Re: [Virtualized eCS] Vbox question and cores (AOS 503) Date: Fri, 10 Dec 2021 15:39:54 -0700 (MST) To: "Virtualized eCS Users Mailing List" <virtualized_ecs_users@2rosenthals.com>

On 2021-12-10, at 21:48:32, Massimo S. wrote:
>
>
>
> Il 10/12/2021 18:20, Doug Bissett ha scritto:
> >On 2021-12-10, at 15:04:59, Massimo S. wrote:
> >>
> >>
> >>
> >>Il 09/12/2021 21:16, Doug Bissett ha scritto:
> >>>On 2021-12-09, at 20:20:28, Massimo S. wrote:
> >>>>
> >>>>Hi all,
> >>>>
> >>>>is it possible to give 3 or 5 cores to an AOS503 guest VM?
> >>>>
> >>>>thanks
> >>>>
> >>>>massimo
> >>>Yes.  AFAIK, you can use up to the number of real cores. HOWEVER, using more than one core will cause problems,
> >>why?
> >>never had one with ACPI
> >>my production servers use 1, 2 or 4 cores, i never had one hang or trap
> >>
> >>>and it will likely not make much difference in performance (it makes very little difference when running a XP, or win 7,
> >>guests).
> >>
> >>no, sorry, they do if you are using real world production servers
> >>
> >>>>From what I see, VBox uses support similar to Hyper Threading, and Hyper Threading is not very friendly to OS/2.
> >>>Try it, and see what happens. I suspect that it will hang after a short period. I haven't tried it for a couple of years,
> something
> >>may have changed (but I doubt it).
> >>
> >>my production servers use 1, 2 or 4 cores, i never had a trap or hang or whatever
> >>my only doubt was MP (3,5,7) not SMP number of cores
> >>
> >>you didn't try that
> >>ok, thanks anyway
> >>
> >>massimo
> >I think you misunderstood. The VBox HOST can run under any number of cores (including Hyper Threading). Using the
> setting in VBox to use more than one core for an OS/2 GUEST will cause trouble because VBox seems to use the same thing
> that Hyper Threading uses. Hyper Threading is not completely compatible with the OS/2 job scheduler, and it will, cause OS/2
> to hang, eventually (usually sooner, than later).
> >
> Doug
>
> the host is WS2019 and the CPU is xeon 8 cores
> i repeat, i don't have any issue using 2 or 4 cores in the gust machine
> with ACPI (AN drv pack on ecs2.2b or AOS503)
>
> maybe this happened with old builds of OS/2, dunno ecs 2.1 or older..
>
> massimo

Okay, I must have misunderstood your question.

I know that I can set 1, 2, 3, or 4 GUEST cores, on a 2 core machine. I do not enable Hyper Threading, in the BIOS, so I only have 2 cores, and it is recommended to not set more cores than actually exist, for guests in VBox.

Hangs happen on ALL versions of OS/2, when Hyper Threading is enabled (at least on real hardware). The OS/2 job scheduler is not compatible with Hyper Threading. Never has been, and probably never will be. It is possible that VBox changed the way they support multiple processors for guests. I do know that OS/2 runs in a 3 core real machine. I have heard of problems trying to use it with a 5 core real machine, although that may have been resolved with the later versions of ACPI.

If that doesn't answer your question, try asking it in a different way, with more detail about what you are trying to do.

--
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From Doug Bissett's ArcaOS system
dougb007 AT ocii.com
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... Those who understand interest, earn it. Those who don't, pay it.

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