SMP/DayStar x4

SMP/DayStar x4

[Sacha Varma]

I have the opportunity to buy a DayStar MP quad-processor card. But I have vague
recollections from looking at the kernel scheduler code that SMP kernels assume
only 2 processors are available.

Can anyone set me straight?

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Re: SMP/DayStar x4

[Steven Hanley]

> only 2 processors are available.
>
> Can anyone set me straight?

very wrong, smp even back when it was added in 1.3.something could
handle more than two AFAIR, it was just very inefficient then. it is now
a lot more efficient and scales a lot better. Dave Miller was using it
on a 14 cpu ultra sparc pre 2.2.0 release, as for ppc, it works on 4 way
ppc, I have no idea how it will work on your specific hardware though.

	See You
	    Steve

--
sjh@wibble.net http://wibble.net/~sjh/
Look Up In The Sky
   Is it a bird?  No
      Is it a plane?  No
         Is it a small blue banana?
YES

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Re: SMP/DayStar x4

[D.J. Barrow]

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Linux supports smp on sparc for ages but linuxppc was
a late starter in the architecture independent part of
smp it only supported 2 cpus & very few interrupt
controllers on ppc upto about a year ago,

Look in smp_boot_cpus in arch/ppc/kernel/smp.c
& the switch(_machine) statment this will give you
some hint on whether your interrupt
controller/motherboard etc will work, if not it may be
a good idea to put printk's in all the case statments
if your not too sure which category your machine falls
into & recompile the kernel.

--- Steven Hanley <sjh@wibble.net> wrote:
>
> > only 2 processors are available.
> >
> > Can anyone set me straight?
>
> very wrong, smp even back when it was added in
> 1.3.something could
> handle more than two AFAIR, it was just very
> inefficient then. it is now
> a lot more efficient and scales a lot better. Dave
> Miller was using it
> on a 14 cpu ultra sparc pre 2.2.0 release, as for
> ppc, it works on 4 way
> ppc, I have no idea how it will work on your
> specific hardware though.
>
> 	See You
> 	    Steve
>
> --
> sjh@wibble.net http://wibble.net/~sjh/
> Look Up In The Sky
>    Is it a bird?  No
>       Is it a plane?  No
>          Is it a small blue banana?
> YES
>
>

=====
D.J. Barrow Linux for S/390 kernel developer
eMail: djbarrow@de.ibm.com,barrow_dj@yahoo.com
Phone: +49-(0)7031-16-2583
IBM Germany Lab, Schönaicherstr. 220, 71032 Böblingen


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