8.1-PRERELEASE: CPU packages not detected correctly

[pluknet]

On 15 July 2010 23:18, Jung-uk Kim <jkim at freebsd.org> wrote:
> On Thursday 15 July 2010 03:07 pm, Jung-uk Kim wrote:
>> On Thursday 15 July 2010 01:56 pm, Andriy Gapon wrote:
>> > on 15/07/2010 19:57 Oliver Fromme said the following:
>> > > In topo_probe(), cpu_high is 0xd, so topo_probe_0xb() is
>> > > called.  But the cpuid 0xb instruction doesn't seem to
>> > > return useful data:  All values are zero already in the
>> > > first level, so cpu_cores remains 0.
>> > >
>> > > Back in topo_probe(), there is a fallback if cpu_cores is
>> > > stil 0:  It assigns mp_ncpu to cpu_cores, so it gets 8
>> > > which is wrong.
>> > >
>> > > I patched topo_probe() so it calls topo_probe_0x4() after
>> > > topo_probe_0xb() if cpu_cores is still 0.  I think this
>> > > is a better fallback procedure.  With this patch, cpu_cores
>> > > gets the value 4 which is the correct one, finally:
>> > >
>> > > FreeBSD/SMP: Multiprocessor System Detected: 8 CPUs
>> > > FreeBSD/SMP: 2 package(s) x 4 core(s)
>> >
>> > Thank you for debugging this issue!
>> > Not sure if this is the best patch that there can be, but its
>> > direction is definitely correct.
>> > As the Intel document says (translated to our x86 mp_machdep.c
>> > terms): if cpu_high >= 0xb then we should execute
>> > cpuid_count(0xb, 0, p) and examine EBX value (p[1]), only if it's
>> > non-zero should we proceed with topo_probe_0xb(), otherwise we
>> > should fall back to topo_probe_0x4, etc.
>> >
>> > I think that your addition achieves this effect, perhaps just not
>> > as explicitly as I would preferred.
>> >
>> > Jung-uk, what do you think?
>>
>> Yes, you're right.  Please try new patch:
>>
>> http://people.freebsd.org/~jkim/mp_machdep2.diff
>
> I uploaded the patch again, it's compile-tested this now.
>

Just tried with the patch against 8.1-rc2.

2x E5520 - OK, no changes
FreeBSD/SMP: Multiprocessor System Detected: 16 CPUs
FreeBSD/SMP: 2 package(s) x 4 core(s) x 2 SMT threads

2x E5440 - now OK
FreeBSD/SMP: Multiprocessor System Detected: 8 CPUs
FreeBSD/SMP: 2 package(s) x 4 core(s)

1x 5050 - OK, no changes
FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
FreeBSD/SMP: 1 package(s) x 2 core(s) x 2 HTT threads

-- 
wbr,
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