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Re: SMP on Alpha 2100 (Sable)

On Sun, 19 Aug 2001, Greg Johnson wrote:

> Now that I can finally boot my AS2100 with an SMP 2.4.x kernel (with
> to the patch from Christopher C. Chimelis), I've found that SMP doesn't
> work so well.  When the first CPU boots, it registers 1082.96 BogoMIPS,
> but when the second comes up it only gets 8.24 BogoMIPS.  /proc/cpuinfo
> reports two processors, but the machine feels like it only has one.
> When I run two jobs on it both get 50% cpu (according to top).
> I have tried removing each processor to make sure they work individually
> (they do).  I also had this problem with 2.2.x but never really
> investigated it.  Perhaps it's a hardware/firmware problem?

That's extremely strange.  FYI, the SMP patch is incorporated into 2.4.9
(along with several of my other patches).  Looks like there may be a
problem with the hardware (perhaps the second socket?), but it's hard to
tell.  If you boot a uniprocessor kernel, do you get the 1082.96 BogoMIPS
on the CPU (try each)?

> Does anyone have any suggestions how I can get both processors fully
> working?  I've attached "dmesg" output along with /proc/cpuinfo and my
> kernel config.  I defined DEBUG_SMP in linux/arch/alpha/kernel/smp.c, so
> it's a little more verbose than usual.

I'll see what I can make of this.


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