MFreleng/8.4 r251256 (by hrs):
Update description of logical CPU handling in the latest releases and remove obsolete sysctl variable machdep.hlt_logical_cpus. MFC after: 3 days
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2020-12-20 02:59:44 +00:00
svn path=/head/; revision=258495
@ -177,16 +177,13 @@
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bugs may generate some problems. Perusal of the archives of
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the &a.smp; may yield some clues.</para>
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<para>&os; will take advantage of HyperThreading (HTT) support
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on &intel; CPUs that support this feature. The
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default &os; scheduler treats the logical processors the same
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as additional physical processors; in other words, no attempt
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is made to optimize scheduling decisions given the shared
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resources between logical processors within the same CPU.
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Because this naive scheduling can result in suboptimal
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performance, under certain circumstances it may be useful to
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disable the logical processors with the
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<varname>machdep.hyperthreading_allowed</varname> tunable.
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<para>&os; will take advantage of SMT (Symmetric MultiThreading,
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also known as HyperThreading on &intel; CPUs) on the supported
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CPUs. The <filename>GENERIC</filename> kernel which is
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installed by default will automatically detect the additional
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logical processors. The default &os; scheduler recognizes
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processor topology on the system and selects logical and
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physical processors to obtain optimal performance.
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The &man.smp.4; manual page has more details.</para>
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<para>&os; will take advantage of Physical Address Extensions
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