Hyper-Threading Technology (HTT) is Intel's trademark for their implementation of the simultaneous multithreading technology on the Pentium 4 micro architecture. It is basically a more advanced form of Super-threading that first debuted on the Intel Xeon processors and was later added to Pentium 4 processors. The technology improves processor performance under certain workloads by providing useful work for execution units that would otherwise be idle, for example during a cache miss.
Hyper threading technology is a technique, which enables a single CPU to act like multiple CPU's. A CPU is made up of many smaller components. At any given time, one of these components might be busy, while the other components are waiting to be utilized. Hyper-Threading enables different parts of the CPU to work on different tasks concurrently. In this way, a CPU with Hyper-Threading appears to be more than one CPU. A CPU with Hyper-Threading has two sets of the circuits, which keep track of the state of the CPU. This includes most of the registers and the instruction pointer. These circuits do not accomplish the actual work of the CPU; they are the temporary storage facilities where the CPU keeps track of what it is currently working on.
Hyper-Threading performance advantages will only be realized when using Operating Systems, which support multiple CPU's. In these operating systems, each CPU with Hyper-Threading will be seen as two CPU's. Operating Systems, which support Hyper-Threading, include Microsoft Windows NT 4.0, Microsoft Windows 2000, Microsoft XP Professional, and most Unix variants.
Some Intel Xeon and Pentium processors support Hyper-Threading. To determine if a CPU supports Hyper-Threading, look for the special "HT" marking on the CPU logo:
