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LinuxElectrons: Intel Hyper-Threading on Linux: Fact or Myth

Mar 01, 2004, 10:00 (0 Talkback[s])

[ Thanks to Jason Greenwood for this link. ]

"The short answer is an Intel P4 processor that fools software into thinking that there are two processors present. Hyper-Threading is a form of simultaneous multithreading technology (SMT), where multiple threads of software applications can be run simultaneously on one processor. This is achieved by duplicating the architectural state on each processor, while sharing one set of processor execution resources. The architectural state tracks the flow of a program or thread, and the execution resources are the units on the processor that do the work: add, multiply, load, etc. Hyper-Threading is a performance enhancement that was an after thought of the original P4 design. Real world performance showed that the P4 had some performance penalties (dead time) caused by the optimizations and algorithms implemented in the pentium4 advanced architecture. With the fast L1 cache and some additional registers, Intel put this dead time to good use. Hence, Hyper-Threading..."

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