Would this system work correctly with FreeBSD 5.3 ?

Sten Spans sten at blinkenlights.nl
Sun Jan 23 02:30:27 PST 2005

On Sat, 22 Jan 2005, Scott Long wrote:

> Sten Spans wrote:
>> On Sat, 22 Jan 2005, Claus Guttesen wrote:
>> - Quad motherboards:
>>   It's a shame that tyan connects all
>>   the pci interfaces on their quad motherboard
>>   to one cpu. The hp/compaq quad proliant has
>>   seperate buses to two cpu's for extra bandwith.
> This is really academic right now since FreeBSD does not take
> topology into account when making scheduling decisions or
> routing interrupts.  Without this affinity, it's only luck
> if you happen to wind up on a CPU that is closer to the data.
> Also, I don't believe that PCI buses are connected to CPUs
> at all.  They are connected via HT-PCI bridges that act as
> normal HT peers.  Only memory is connected directly to the CPU.
> But I might be wrong.

True, motherboards with this setup have extra ht-pci bridges.
The amd reference motherboards have this design. But most motherboards
don't use this setup to cut costs ( less bridges and traces needed ) and
because it requires more cpu sockets to be populated ( although
this isn't such a big problem on a quad motherboard ).

Sten Spans

"There is a crack in everything, that's how the light gets in."
Leonard Cohen - Anthem

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