Multi-CPU settings

brian_westerman

Sep 28, 2006

Hi all,

I was wondering with all of the new Dual (and now quad) core CPU's that
are available if it would be a good idea to set some "rules of thumb"
about what is efficient to set for these CPU's

For instance, I think it's okay to specify 2 CPUs in the hercules
config if you have a P4 with HyperThreading, but If you have a Dual
Core CPU, does that still only leave it okay to specify 2, or do they
also have HT in which case could you specify 4 CPU's. The same goes
for the new QUAD core stuff, if they also support HT, would that mean
we can specify 8 CPU's?

Does anyone have a good idea of what would be acceptable?

12:46 am

Re: Multi-CPU settings

dekel35

Sep 29, 2006

--- In hercules-390@yahoogroups.com, "brian_westerman"
<Brian_Westerman@...> wrote:
>
> I give it 1GB, It never uses it all but I figure that the smaller the
> chance that anything will page the better.
>
> Does anyone have a dual core CPU that they can check to see if it would
> be 2 CPU's or 4 (assuming it also has hyperthreading)?
>
> Thanks
>
> Brian

I have a dual core, and after experimenting different scenarios I
concluded that the best would be to map each physical CPU to an
emulated one. If you have the extreme version (i.e., with HT for each
core processor) you might want to try increasing the number to 4.
In any case defining LESS emulated processors than there actually are
is not recomended.

8:44 am

Re: Multi-CPU settings

Jay Maynard

Sep 29, 2006

On Fri, Sep 29, 2006 at 08:44:39AM -0000, dekel35 wrote:
> In any case defining LESS emulated processors than there actually are
> is not recomended.

Why not? It works fine. The recommendation used to be to define one fewer
emulated CPU than there are physical CPUs in the system, to allow one
processor to handle system overhead and other non-emulation tasks; this
isn't so necessary any more, but depending on your system load, might still
be a good idea.

Hercules had some SMP-on-SMP issues until 3.03, but those have been fixed
(at least for x86, x86-64, and 32-bit PowerPC host platforms).
--
Jay Maynard, K5ZC http://www.conmicro.cx
http://jmaynard.livejournal.com http://www.tronguy.net
http://www.hercules-390.org (Yes, that's me!)
Buy Hercules stuff at http://www.cafepress.com/hercules-390

11:14 am