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Has anyone turned off hyper threading?

Discussion in 'Desktop & Laptop Computers Forum' started by DaveP, Apr 14, 2005.

  1. DaveP

    DaveP
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    I'm using a P4 2.8Ghz HT processor in my HTPC. When I'm running DScaler it puts one half of the processor up to the max of 50%.

    Would I be better off turning off the HT feature to allow it to use more if needed?

    Has anyone run any tests to see if there are any advantages to turning off the feature?

    I'm in the process of building a new HTPC and I've turned this off for now.

    Dave
     
  2. Skunkpipe

    Skunkpipe
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    Hyper threading essentially mimics a second core by giving work to under-utilised execution units which is good if there are under-utilised execution units to work with - if not HT doesn't bring any benefit. Dual Core processors when they arrive will do the job 'properly'

    As for advantages of turning it off; can't think of any - performance will be worse - you *might* get a reduction in CPU temp, but this is just speculation on my part and might be worth a test
     
  3. KraGorn

    KraGorn
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    I turned it off to stop occasional glitches on playback. In TheaterTek I'd get sporadic sudden 'jumps', sort of like TT suddenly decided to skip a 1/2 second or so, it wasn't a pause it was a skip. These totally stopped when I disabled HT, something that is not an uncommon experience it would seem.

    Since video playback is essentially a linear process then a second pseudo-processor actually does very little, I know there are supposed to be some parts of the playback chain which can multi-thread but in the end it's barely detectable.

    You'd be best off enabling HT when you install XP, I'm not sure if HT support is like dual-processor support and uses a different kernel, in any case try it enabled and see if you get the sort of problem I described, if you do then you can disable it later.
     
  4. DaveP

    DaveP
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    Thanks Kragorn, I shall run with it off for a while. I have noticed jumps and with sme playback.

    When I look at Performance in Task manager the right hand graph has maxed out at 50% so it just seems to be a bottleneck.

    Dave

    PS XP will automatically instal HT if a processor is swapped or HT is turned on. It comes is as a new hardware found wizard.
     
  5. KraGorn

    KraGorn
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    If you're getting one of the 'processors' clipping then you need to reduce the loading, having HT enabled doesn't add any significant extra CPU 'horsepower'.

    What processes are consuming lots of CPU time? Simple hardware-based DVD playback shouldn't use more than around 20% on a 3G P4 in my experience with TT.

    Thanks for the info about XP's ability to add HT on the fly, useful to know.
     
  6. DaveP

    DaveP
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    Task Manager shows DScaler as the culprit running at the full 50%.

    I'm feeding it with RGB from sky through my Sweetspot card.

    When I put the sweetspot in my new PC I'll check it out with HT turned off.


    Dave
     
  7. KraGorn

    KraGorn
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    In that case you seem to have DScaler configured to highly, ie. you're asking it to do too much work and its' running out of CPU power, this isn't an HT-related problem on the face of it.
     

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