Please help me with building a Multi-Core "box"

QNX USERS QNX6 - OS
1

I need to build a QNX multi-core x86 machine. Can anyone recommend CPU, MB, etc? Does it matter? From what I’ve seen on this forum my best bet is to install Neutrino SP3, since it appears to support multi cores. Is this correct?

Thanks

2

Any of the Neutrino releases you can get your hands on are going to support SMP, but since you can easily access the combined 6.3.2 release now from
foundry27.com, I’d recommend starting with the latest version.

As far as x86 is concerned, the only thing to watch out for is that some of the AMD’s have automatic frequency scaling across the CPU’s that throws
the timing for a loop (in particular the instrumentation). We have a tentative fix for that that is heading into the source soon (again the live OS source
on foundry27) but if you can avoid it you might want to. Look for BIOS options to control that behaviour.

Other than that, x86 SMP is pretty clear sailing.

3

I had problems with a SCSI driver under 6.2 using SMP, but from 6.3 on there’s been no problem. I don’t imagine that there is much difference between SMP and Multi-core.

4

There is a difference between SMP and Multi-core ( depending on manufactuers ) and it has to do with how the cache is shared. But as far as I know the OS doesn’t try to deal with that ( nor does it tries do deal with a NUMA configuration )

5

The work around for now is to set the nohalt option to procnto in your build file. (ie procnto-smp-instr -h)

Colin

6

Thank you all for all the replies. What about motherboards? I’ve seen some reference to a couple of Asus boards with LGA775 sockets. Any particular models/brands that work really well?

7

In theory as long as the MB support MP 1.2 you should be ok that covers pretty much all the MB today.

As for work really well, my experience so far is that ALL motherboards I’ve tried with dual socket works just fine as well as CPU with multi-core ( aside the gotcha for AMD ).

It mostly come down to the on board devices ( network , grx ) that may or may not be supported.

There are some architecture that will give more processing power, but it changes every 3-6 months or so and QNX6 isn’t always capable of getting the maximum out of it ( I’m thinking NUMA ) or how the cache are setup in the cpu etc.

8

We had some issues with some mp-cpu-cards(full system cards) where special drivers made handling a bit tricky, but we still got all cards running until now :slight_smile: