Mailing List Archived Message #177

From: "Doug Bissett" <> Full Headers
Undecoded message
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" <>

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.

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

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