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MFC r258495:

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Update description of logical CPU handling in the latest releases and
remove obsolete sysctl variable machdep.hlt_logical_cpus.

Approved by:	re (hrs)
This commit is contained in:
mav 2013-12-04 10:54:23 +00:00
parent 80dc28ceef
commit d0d1c645c4
1 changed files with 7 additions and 10 deletions
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17
release/doc/en_US.ISO8859-1/hardware/article.xml
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@ -177,16 +177,13 @@
bugs may generate some problems. Perusal of the archives of
the &a.smp; may yield some clues.</para>
<para>&os; will take advantage of HyperThreading (HTT) support
on &intel; CPUs that support this feature. The
default &os; scheduler treats the logical processors the same
as additional physical processors; in other words, no attempt
is made to optimize scheduling decisions given the shared
resources between logical processors within the same CPU.
Because this naive scheduling can result in suboptimal
performance, under certain circumstances it may be useful to
disable the logical processors with the
<varname>machdep.hyperthreading_allowed</varname> tunable.
<para>&os; will take advantage of SMT (Symmetric MultiThreading,
also known as HyperThreading on &intel; CPUs) on the supported
CPUs. The <filename>GENERIC</filename> kernel which is
installed by default will automatically detect the additional
logical processors. The default &os; scheduler recognizes
processor topology on the system and selects logical and
physical processors to obtain optimal performance.
The &man.smp.4; manual page has more details.</para>
<para>&os; will take advantage of Physical Address Extensions