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Simultaneous Multithreading (SMT) Manager - enable or disable hyperthreading cores, or display your current CPU topology.
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Enable or disable logical cores, or display your current CPU topology.

NAME - View current status of CPU topology or set logical cores
to offline or online.

SYNOPSIS [options]

  --help        Prints this help.
  --online      Enables all logical CPU cores.
  --offline     Disables all logical CPU cores.
  --manual      Display man page of this script.


--help  Prints standard help information and options that are available.

        Attempts to enable all logical cores if they are already offline.
        If they are not offline, no changes will be made and no secondary
        topology print out will occur.

        Performs the opposite action as --online.

        Displays help page as a man page and also displays description and


This script provides the user details about whether each CPU is physical
or logical. When provided an optional parameter, the logical CPUs can be
enabled or disabled.

Why would one want to disable logical cores? Logical CPU cores with a high
nice value steal more CPU time than a physical core. This is noticeable
when multitasking heavily, for instance, building a kernel with 8 cores as
a very nice (+20) task while running a greedy single threaded application.

By disabling the logical cores, the behavior and responsiveness of the
system will be more predictable, but throughput will drop as a whole for
heavy multi- threaded batch jobs.
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