NewsFactor: A Linux Mystery: Configuring for Virtual Processors

“Until recently, application multithreading–breaking up pieces
of a monolithic application to allow parallel processing, which
speeds up performance–was not as beneficial with Linux as with
other Unix-related operating systems. Then companies like Red Hat
did a ground-up redesign of multithreading libraries that
eliminated bottlenecks, such as the hard limit on the number of
threads an application could create.

“But no sooner was that problem solved than Intel came out with
hyperthreading, or simultaneous multithreading, a technique that
makes a single physical processor appear to an operating system as
if it were two logical processors. Hyperthreading support was built
into the Linux 2.4 and 2.5 code bases, but some experts note there
are still some hitches that could warrant turning the feature
off…”

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