Re: HT bug in some Intel CPUs ?

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Thu, Aug 06, 2009 at 08:55:39AM -0600, Greg Oster wrote:
> Manuel Bouyer writes:
> > Hi,
> > after fighting with a upgrade from NetBSD-3 to NetBSD-5/i386 of two
> > identical  servers, I came to the conclusion that hyperthreading is
> > broken on this CPU, causing corrupted registers or memory reads
> > (I couldn't determine which).
> > The CPU is:
> > cpu0: Intel (686-class), 3000.22 MHz, id 0xf4a
> > cpu0: features bfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR>
> > cpu0: features bfebfbff<PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX>
> > cpu0: features bfebfbff<FXSR,SSE,SSE2,SS,HTT,TM,SBF>
> > cpu0: features2 641d<SSE3,MONITOR,DS-CPL,CID,xTPR>
> > cpu0: features3 20100000<EM64T>
> > cpu0: "Intel(R) Xeon(TM) CPU 3.00GHz"
> > cpu0: I-cache 12K uOp cache 8-way
> > cpu0: L2 cache 2 MB 64B/line 8-way
> > cpu0: ITLB 4K/4M: 64 entries
> > cpu0: DTLB 4K/4M: 64 entries
> 
> Interesting... the CPUs in the box I'm having grief upgrading from 
> NetBSD-3 to NetBSD-5/i386 look like this:
> 
> cpu0: Intel (686-class), 3000.35 MHz, id 0xf41
> cpu0: features bfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR>
> cpu0: features bfebfbff<PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX>
> cpu0: features bfebfbff<FXSR,SSE,SSE2,SS,HTT,TM,SBF>
> cpu0: features2 641d<SSE3,MONITOR,DS-CPL,CID,xTPR>
> cpu0: features3 20100000<EM64T>
> cpu0: "Intel(R) Xeon(TM) CPU 3.00GHz"
> cpu0: I-cache 12K uOp cache 8-way
> cpu0: L2 cache 1 MB 64B/line 8-way
> cpu0: ITLB 4K/4M: 64 entries
> cpu0: DTLB 4K/4M: 64 entries
> cpu0: using thermal monitor 1
> cpu0: calibrating local timer
> cpu0: apic clock running at 200 MHz
> cpu0: 32 page colors
> 
> They don't show up as hyperthreaded in 3.0, but do in 5.0.1.

Did you try a SMP 3.0 kernel ? Maube a ACPI issue ?

> > [...]
> > Did someone else notice something similar, or have informations about
> > such bug ?
> 
> I'd like to think that whatever issue you're seeing is the same one I 
> have... Would disabling hyperthreading help at all to provide a 
> datapoint?

That would, of course. Now there may be other issues :)

> (After an uptime of 330+ days, having 3 hangs in a week 
> isn't giving me warm, fuzzy feelings :-/ The machine in question 
> is an IBM x336 that has been rock-stable under 3.0)

I also have a similar box: same motherboard, with two
cpu0: Intel (686-class), 3000.23 MHz, id 0xf43
3Ghz Xeon that is also due for upgrade. I'll see if it can run
SMP without hyperthreading. I'll probably test this this in a few
days.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--