Processor Identification

The following schemes are used to identify logical processors in a system:

The number of a logical CPU is defined as the corresponding position of this CPU bit in the kernel affinity bit-mask. Use the cpuinfo utility, provided with your Intel MPI Library installation, or the cat /proc/cpuinfo command to find out the logical CPU numbers.

The three-level hierarchical identification uses triplets that provide information about processor location and their order. The triplets are hierarchically ordered (package, core, and thread).

See the example for one possible processor numbering scenario with two sockets, four cores (two cores per socket), and eight logical processors (two processors per core).

Note

Logical and topological enumerations are not the same.

Table 3.2-1 Logical Enumeration

0

4

1

5

2

6

3

7

Table 3.2-2 Hierarchical Levels

Socket

0

0

0

0

1

1

1

1

Core

0

0

1

1

0

0

1

1

Thread

0

1

0

1

0

1

0

1

Table 3.2-3 Topological Enumeration

0

1

2

3

4

5

6

7

Use the cpuinfo utility to identify the correspondence between the logical and topological enumerations. See Processor Information Utility for more details.