Driver Reference Table (DRT)Great thanks to blueelvis for automating the counting of drivers. Griffith, Microsoft MVP (jcgriff. Elmer Be. Fuddled. Geoff Maggi (Laxer). Will Watts (Will Watts). Microsoft MVP). , and blueelvis. Hyper- threading - Wikipedia. In this high- level depiction of HTT, instructions are fetched from RAM (differently colored boxes represent the instructions of four different programs), decoded and reordered by the front end (white boxes represent pipeline bubbles), and passed to the execution core capable of executing instructions from two different programs during the same clock cycle. It first appeared in February 2. Xeon server processors and in November 2. Pentium 4 desktop CPUs. ![]() Free downloads, tools, how-to guides, best practices, and community forums to help you upgrade, deploy, manage, and support Windows devices and PCs.
The main function of hyper- threading is to increase the number of independent instructions in the pipeline; it takes advantage of superscalar architecture, in which multiple instructions operate on separate data in parallel. With HTT, one physical core appears as two processors to the operating system, allowing concurrent scheduling of two processes per core. In addition, two or more processes can use the same resources: if resources for one process are not available, then another process can continue if its resources are available. In addition to requiring simultaneous multithreading (SMT) support in the operating system, hyper- threading can be properly utilized only with an operating system specifically optimized for it. Architecturally, a processor with Hyper- Threading Technology consists of two logical processors per core, each of which has its own processor architectural state. Each logical processor can be individually halted, interrupted or directed to execute a specified thread, independently from the other logical processor sharing the same physical core. These resources include the execution engine, caches, and system bus interface; the sharing of resources allows two logical processors to work with each other more efficiently, and allows a logical processor to borrow resources from a stalled logical core (assuming both logical cores are associated with the same physical core). A processor stalls when it is waiting for data it has sent for so it can finish processing the present thread. The degree of benefit seen when using a hyper- threaded or multi core processor depends on the needs of the software, and how well it and the operating system are written to manage the processor efficiently. This allows a hyper- threading processor to appear as the usual . When execution resources would not be used by the current task in a processor without hyper- threading, and especially when the processor is stalled, a hyper- threading equipped processor can use those execution resources to execute another scheduled task. The minimum that is required to take advantage of hyper- threading is symmetric multiprocessing (SMP) support in the operating system, as the logical processors appear as standard separate processors. It is possible to optimize operating system behavior on multi- processor hyper- threading capable systems. For example, consider an SMP system with two physical processors that are both hyper- threaded (for a total of four logical processors). If the operating system's thread scheduler is unaware of hyper- threading, it will treat all four logical processors the same. If only two threads are eligible to run, it might choose to schedule those threads on the two logical processors that happen to belong to the same physical processor; that processor would become extremely busy while the other would idle, leading to poorer performance than is possible by scheduling the threads onto different physical processors. This problem can be avoided by improving the scheduler to treat logical processors differently from physical processors; in a sense, this is a limited form of the scheduler changes that are required for NUMA systems. History. The HEP pipeline could not hold multiple instructions that belong to the same process. Only one instruction from a given process was allowed to be present in the pipeline at any point in time. Should an instruction from a given process block in the pipe, instructions from the other processes would continue after the pipeline drained. US patent for the technology behind hyper- threading was granted to Kenneth Okin at Sun Microsystems in November 1. Back at the time, CMOS process technology was not advanced enough to allow for a cost- effective implementation. It was also included on the 3. GHz Northwood- based Pentium 4 in the same year, and then remained as a feature in every Pentium 4 HT, Pentium 4 Extreme Edition and Pentium Extreme Edition processor since. Previous generations of Intel's processors based on the Core microarchitecture do not have Hyper- Threading, because the Core microarchitecture is a descendant of the P6 microarchitecture used in iterations of Pentium since the Pentium Pro through the Pentium III and the Celeron (Covington, Mendocino, Coppermine and Tualatin- based) and the Pentium II Xeon and Pentium III Xeon models. Intel released the Nehalem (Core i. November 2. 00. 8 in which hyper- threading made a return. The first generation Nehalem contained four cores and effectively scaled eight threads. Since then, both two- and six- core models have been released, scaling four and twelve threads respectively. The next model, the Itanium 9. Poulson), features a 1. CPU cores with support for eight more virtual cores via hyper- threading. Tom's Hardware states: . As one commentary on high- performance computing from November 2. Depending on the cluster configuration and, most importantly, the nature of the application running on the cluster, performance gains can vary or even be negative. The next step is to use performance tools to understand what areas contribute to performance gains and what areas contribute to performance degradation. As a result, performance improvements are very application- dependent. The Pentium 4 . In other words, overall processing latency is significantly increased due to hyper- threading, with the negative effects becoming smaller as there are more simultaneous threads that can effectively use the additional hardware resource utilization provided by hyper- threading. Windows 2. 00. 0 and Linux older than 2. Furthermore, they claimed that SMT increases cache thrashing by 4. Potential solutions to this include the processor changing its cache eviction strategy, or the operating system preventing the simultaneous execution, on the same physical core, of threads with different privileges. Ars Technica. Retrieved 2. Marr; Frank Binns; David L. Hill; Glenn Hinton; David A. Alan Miller; Michael Upton (2. Retrieved 2. 01. 5- 0. Retrieved 2. 01. 5- 0. Retrieved 2. 01. 4- 0. Thomadakis (2. 01. Texas A& M University. Retrieved 2. 01. 4- 0. Retrieved 2. 01. 1- 0. Tomshardware. com. Retrieved 2. 01. 7- 0. Retrieved 2. 01. 1- 0. Retrieved 2. 01. 1- 0. Tomshardware. com. Retrieved 2. 01. 1- 0. Retrieved 1. 2 November 2. Retrieved 2 March 2. Replay: Unknown Features of the Net. Burst Core. Retrieved 2. April 2. 01. 1. Retrieved 2. February 2. 01. 5. November 2. 01. 3. Retrieved 2. 6 February 2. December 2. 01. 4. Retrieved 2 March 2. Per- cpu load can be observed using the mpstat utility, but note that on processors with hyperthreading (HT), each hyperthread is represented as a separate CPU. For interrupt handling, HT has shown no benefit in initial tests, so limit the number of queues to the number of CPU cores in the system. Retrieved 2. 01. 2- 0. Information Resources Management Association. ISBN 9. 78. 14. 66. Retrieved 2. 01. 2- 0. Archived from the original on 1. June 2. 01. 1. Retrieved 5 April 2. The Register. Retrieved 1. January 2. 01. 4. Retrieved 2. 01. 7- 0. Retrieved 2. 01. 6- 0.
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