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Lets throw some light on computer terminology When I started reading semiconductor stuff and computer related articles.I was bombarded with a bevy of words which didn't make any sense, i had to peruse wiki chip and digit before they made sense.I am talking about the jargon , the terms that make computer literature a tough thing to read.
Now i try to make some commonly misunderstood terms understandable!
first up hyper threading.(source Wiki/Intel/UC Berkeley)
Hyperthreading is a term often associated with Intel core series and old Pentium series.
it is claimed to improve the processor efficiency by up to 30%.
What exactly is hyper threading? Is it really worth it. Lets analyze.
Intel launched HT on Pentium series, where they claimed the processor would be able to do 2 tasks simultaneously. With HT they introduced a concept called virtual core.
Any processor has an execution unit(remember ALU!) , Fetch ,decode unit and a architectural unit which stores the state of registers.
In HT this architectural unit is utilized as the logical core i.e. when the OS has two tasks one of the task is operated by the execution unit , while the logical core queues the task and as soon as the execution unit is waiting( due to a wrong branch prediction* or a cache miss). this queued task is given to execution unit.So we can summarize HT as pipe-lining within a core.(simple isn't it)
For a application(including OS) to be efficient , it should know that the processor is HT, now if this is the case then the application is called Symmetric multiprocessing ready(jargon again)
why not any application, imagine a case i7 920( 4C/8T) , now there are four tasks ,You have 4 cores and 8 virtual cores. Now if your OS has 4tasks, it may treat 4 logical cores(2 physical cores) as 4 physical cores and load them ,leaving 2 physical cores unattended.
Thus 2 physical core with 4 task gets overloaded and the other two physical cores become idle, you don't want that do you after shelling out 14k!!
and with HT according to tom's hardware a Pentium clocked @ 3.00GHz had the same performance as a overclocked 3.6GHz chip.( that's some gain isn't it?)
Thus you get 8 Logical cores (not always) in a 4Core CPU.Now this combined with Turbo boost (will explain later), is what makes i7 so superior.
I hope this helps, if you guys feel this is good i will add further topics, even you can ask for one!!
*Branch predictor is a unit which predicts what the next branch in case of a if_else or switch statement. It predicts based on the previous iterations. a wrong branch prediction ca be very costly as the entire pipeline in the processor will have to be flushed.)
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Originally Posted by rajan1311 
