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04.11.2015 07:44  
OlegON
В очередной раз озадачился, нужно ли включать эту опцию. Смущала рекомендация делать это для i7 и выше. Нагуглил следующую информацию.



Цитата:
It can reasonably only refer to Intel Core i7 CPUs released or announced per spec by that time. That would be the Bloomfield processors, based on the Nehalem microarchitecture, which moved the memory controller from the Northbridge onto the CPU (which AMD had done in 2003 with the Opteron/AMD64) and introduced QuickPath Interconnect/QPI (as pendant to AMD's HyperTransport) for CPU/CPU and CPU/IOH (IO hub, ex-Northbridge) interconnection.

The Bloomdale i7 CPUs were the first entries in the new Core i{3,5,7} naming scheme. So when that Linux doc text was written, i7 didn't specifically refer to the Core i7 as opposed to i5 (first in 09/2009) or i3 (first in 01/2010), but in all likelihood to the new Nehalem microarchitecture with its integrated memory controller and QPI.

There's an Intel press release from 11/2008 on the i7 (Intel Launches Fastest Processor on the Planet) that states that the Core i7 processor more than doubles the memory bandwidth of previous Intel "Extreme" platforms, but doesn't mention NUMA at all.

The reason is, I think, that NUMA doesn't matter for desktop PCs, not even for "extreme" ones.

NUMA matters for expensive servers that have several CPU sockets (not just several cores on one socket) with dedicated physical memory access lanes (not just one memory controller), so that each CPU has its dedicated local memory, which is "closer" to it than the memory of the other CPUs. (Think 8 sockets, 64 cores, 256 GB RAM.) NUMA means that a CPU can also access remote memory (the local memory of another CPU) in addition to its own local memory, albeit at a higher cost. NUMA is the synthesis of a shared memory architecture like SMP, where all memory is equally available to all cores, and a distributed memory architecture like MPP (Massively Parallel Processing), that gives each node a dedicated block of memory. It is MPP, but it looks like SMP to the application.

Desktop motherboards don't have dual sockets and Intel desktop CPUs including extreme i7 editions lack the additional QPI link for dual socket configuration.
иными словами NUMA на односокетных машинах не работает, поэтому включать ее нет смысла.
 
 
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