Operating Systems > macOS
What the fuck is this shit???
boris_cleto:
quote: Pardon my ignorance, but what is 'numa'?
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NUMA - Non-uniform memory access
quote: NUMA stands for non-uniform memory access. It's a design that can be used to build scalable systems. Basically you take zero or more processors, a memory and bus controller, and some RAM and bundle them together into a unit. (Typically this unit is on its own circuit board.) Attach two or more of these units together with a high-speed interconnect and you've got a NUMA system. Processor A on board 1 has local access to memory bank I, but has to go across the interconnect to reach memory bank II or board 2. Hence, non-uniform.
The Power Mac G5 is not a NUMA system. All memory access goes through the Apple-designed System Controller. The System Controller connects the processor(s) to memory and graphics, and to the HyperTransport fabric that provides access to the internal storage and expansion slots.
So if processor 1 wants to get at any piece of memory in the system, it goes through the system controller and into the RAM to get it. Processor 2 does exactly the same thing. Therefore the Power Mac G5 is not a NUMA system, because all memory accesses are uniform.
Now, at least in theory it would be possible for Apple to design a NUMA system around the Power Mac G5 architecture. They could design a System Controller to HyperTransport to System Controller link that basically connects two Power Mac G5-style systems together and allows them to function as a single computer. (Note that we're not talking about clustering here; we're talking about one computer with more than two processors.) But the Power Mac G5 is not it.
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Laukev7:
Thank you for this information, Boris. If I understand correctly, each processor gets its own memory. But what is the point?
mushrooomprince:
Just one question: If the G5 powermac's aren't supposed to be shipping until august how could they get a hold of a G5 machine to do these tests ?
Pissed_Macman:
Maybe they based this on Apple's tests.
M51DPS:
Speaking of memory, does the new G5 have L3 cache? It doesn't look like it's present.
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