43 lines
1.5 KiB
Plaintext
43 lines
1.5 KiB
Plaintext
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On some larger systems, memory has non-uniform access times. It is organized
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in so-called NUMA-nodes. A NUMA node is a part of memory which is accessible
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faster for some particular subset of processors.
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# lscpu
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Architecture: x86_64
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CPU op-mode(s): 32-bit, 64-bit
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Byte Order: Little Endian
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CPU(s): 24
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On-line CPU(s) list: 0-23
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Thread(s) per core: 2
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Core(s) per socket: 6
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Socket(s): 2
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NUMA node(s): 2
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Vendor ID: GenuineIntel
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CPU family: 6
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Model: 45
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Stepping: 7
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CPU MHz: 1200.000
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BogoMIPS: 4588.34
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Virtualization: VT-x
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L1d cache: 32K
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L1i cache: 32K
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L2 cache: 256K
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L3 cache: 15360K
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NUMA node0 CPU(s): 0-5,12-17
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NUMA node1 CPU(s): 6-11,18-23
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This machine has two NUMA nodes and 24 processors (they are called CPUs, but
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that is not very precise). Half of them belongs to NUMA node0 and the second
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half to node1.
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When a processor accesses data that lies in its NUMA node, it is faster than
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accessing data from some other node. The local access is called LMA and the
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remote one is called RMA.
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The NUMATOP tool watches what happens around the NUMA nodes and it sees both
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LMAs and RMAs. If the machine has only one NUMA node, only LMAs can be seen.
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The test tries to trigger LMAs and check whether NUMATOP registers it. If we
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have more than one NUMA node, we test RMAs as well.
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