Hyperthreading and Task Manager

Discussion in 'Processors and motherboards Intel' started by hamltnblue, Sep 8, 2013.

  1. hamltnblue

    hamltnblue Active Member

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    When looking at the task manager with a 4 core i7 processor you see 8 cores in the CPU usage history.
    Which of the 8 boxes represent the physical cores and which do so with the logical cores? Or are they all logical cores.
    I'm asking because I had always thought the boxes 5 thru 8 were logical.
    I now have a single threaded program showing all activity on the 8th box.
    Thanks
     
  2. sykozis

    sykozis Ancient Guru

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    Cores 0, 2, 4, 6 = Physical
    Cores 1, 3, 5, 7 = Logical
     
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  3. mbk1969

    mbk1969 Ancient Guru

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    Aren`t all cores logical when hyperthreading is on?
     
  4. FatBoyNL

    FatBoyNL Ancient Guru

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    Not sure if trolling. That's just wrong.

    The multiple graphs in Task Manager all represent logical processors.
     

  5. tsunami231

    tsunami231 Ancient Guru

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    if that was true it would mean there is no physical core....

    My take is when there HT involved the even are the actual cores and odd are ht cores
     
  6. airbud7

    airbud7 Ancient Guru

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    This^...My i3 is...

    Cores 0, 2= Physical
    Cores 1, 3= Logical
     
  7. BLEH!

    BLEH! Ancient Guru

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    For my i7 (Xeon, technically), when I have HT on, the "real" cores are 0, 1, 2, 8, 9 and 10, with the logical cores being 3, 4, 5, 6, 7 and 11 for some strange reason. HW Monitor supports this through the temps. I normally run HT off for better performance/higher overclock.
     
  8. mbk1969

    mbk1969 Ancient Guru

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    From wikipedia:

    For each processor core that is physically present, the operating system addresses two virtual or logical cores, and shares the workload between them when possible. The main function of hyper-threading is to decrease the number of dependent instructions on the pipeline. It takes advantage of superscalar architecture (multiple instructions operating on separate data in parallel). They appear to the OS as two processors, thus the OS can schedule two processes at once. In addition two or more processes can use the same resources. If one process fails then the resources can be readily re-allocated.
     
  9. hamltnblue

    hamltnblue Active Member

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  10. FatBoyNL

    FatBoyNL Ancient Guru

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    Thanks for this hyper-threading article. Wiki also has this on Task Manager, see http://en.wikipedia.org/wiki/Windows_Task_Manager.
    Couldn't find any good Microsoft and/or Intel docs, but this guy explains sockets, physical cores and logical processors in Task Manager pretty well:
    http://www.itechtics.com/physical-socket-physical-core-logical-processor/ and
    http://www.itechtics.com/cpu-utilization-cores-windows-8/

    Below some examples taken from the Win8 Task Manager:

    Intel i7-2600K has:
    1 Socket
    4 Physical cores
    8 Logical processors (and therefore 8 graphs)

    AMD Phenom II X6 1045T has:
    1 Socket
    6 Physical cores
    6 Logical processors (and therefore 6 graphs)
    (see http://en.wikipedia.org/wiki/File:W8_Task_Manager.png)

    Final conclusion: Windows OS Task Manager graphs only show Logical Processors :)
     

  11. sykozis

    sykozis Ancient Guru

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    Actually, my answer is correct based on the OP's question.

    Maybe you should have actually read the OP's post....
     
  12. mbk1969

    mbk1969 Ancient Guru

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    According to this cores 0 and 1 differ only by duplicated sections (while the main section is shared). And those duplicated sections are the same, just each core has its own instance. And tell me what difference do you see here - as each core represented in Task manager shares main part and has its own additional part? I.e. both cores are identical from hardware point of view.
     
    Last edited: Sep 10, 2013
  13. FatBoyNL

    FatBoyNL Ancient Guru

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    I'm sure that I don't get you. What do you mean exactly?
    My point is that Windows Task Manager can only show logical processors, not physical ones.
    Could you please link me to the source of your information?
     
  14. ViperXtreme

    ViperXtreme Ancient Guru

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    i remember my i3 using core 0 and core 2 when its running a 2 thread application, rarely use other pattern otherwise (like core 1 and3 or 1 and 2)
     

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