Dual core processor not used under XP pro x64

Discussion in 'Windows 64bit' started by =?Utf-8?B?RXJpYyBBcHBlbG1hbnM=?=, Dec 15, 2006.

  1. Hello,
    I've just got my new Dell precison 690 with two dual core Xenon Intel
    processor. I've install XP pro x64. No problem, windows sees my
    processors..... but only uses one of them!
    By default the bios had enabled Hyper threading and I could only use a
    maximum of 12,5 % of my processor. Now that I have disabled HT, I can use
    25%, but I can't find a way to use the whole power available.
    I checked affinity and my main application is allowed to uses all the
    processors....but it does not.
    Any ideas ?
    --
    Eric Appelmans
    =?Utf-8?B?RXJpYyBBcHBlbG1hbnM=?=, Dec 15, 2006
    #1
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  2. You'll undoubtedly need a BIOS update and/or a system driver.

    --
    Charlie.
    http://msmvps.com/xperts64


    "Eric Appelmans" <> wrote in message
    news:...
    > Hello,
    > I've just got my new Dell precison 690 with two dual core Xenon Intel
    > processor. I've install XP pro x64. No problem, windows sees my
    > processors..... but only uses one of them!
    > By default the bios had enabled Hyper threading and I could only use a
    > maximum of 12,5 % of my processor. Now that I have disabled HT, I can use
    > 25%, but I can't find a way to use the whole power available.
    > I checked affinity and my main application is allowed to uses all the
    > processors....but it does not.
    > Any ideas ?
    > --
    > Eric Appelmans
    Charlie Russel - MVP, Dec 15, 2006
    #2
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  3. * Eric Appelmans:
    > Hello,
    > I've just got my new Dell precison 690 with two dual core Xenon Intel
    > processor.


    What "dual core" Xeon (the only "Xenon" processor is in the Xbox 360)
    processors do you have? The Precision 690 is offered with XEON 5100 and
    XEON 5300 which both are Core based but also can take the XEON 5000 series.

    XEON 5000 does Hyperthreading while XEON 5100 and 5300 do not...

    > I've install XP pro x64. No problem, windows sees my
    > processors..... but only uses one of them!
    > By default the bios had enabled Hyper threading and I could only use a
    > maximum of 12,5 % of my processor. Now that I have disabled HT, I can use
    > 25%, but I can't find a way to use the whole power available.
    > I checked affinity and my main application is allowed to uses all the
    > processors....but it does not.
    > Any ideas ?


    How many cpus does the taskmanager show (set it to "one diagram per cpu"!)?

    And are you sure that your application (what application? Does it have a
    name?) is multithreaded and supports SMP? Just because its affinity can
    be to any of the logical processors doesn't mean it supports multiple
    processors.

    What you describe looks very much like an application that can't use
    multiple processors. If all CPUs are present in taskmanager then there
    is nothing wrong with your system or Windows...

    Benjamin
    Benjamin Gawert, Dec 16, 2006
    #3
  4. If Windows sees the processors, which it clearly does, then the application
    itself is probably not written to use more than a single processor. If this
    is the case, then turning off hyperthreading is probably a good idea
    (actually it's probably a good idea anyway on a 4 core box that is used by a
    single person.)

    --
    Charlie.
    http://msmvps.com/xperts64


    "Eric Appelmans" <> wrote in message
    news:...
    > Thanks for those info.
    > My processors are 5000 series (as they can be hyperthreaded).
    > The task manager actually shows me 8 processors (2 dual cores
    > hyperthreaded), so it's clear that windows sees the processors.
    > I thought of an option or an update that could change the way windows uses
    > the processor.
    > I'll check with my software (CATIA) help deskif it accepts multiple
    > processor.
    > --
    > Eric Appelmans
    >
    >
    > "Benjamin Gawert" wrote:
    >
    >> * Eric Appelmans:
    >> > Hello,
    >> > I've just got my new Dell precison 690 with two dual core Xenon Intel
    >> > processor.

    >>
    >> What "dual core" Xeon (the only "Xenon" processor is in the Xbox 360)
    >> processors do you have? The Precision 690 is offered with XEON 5100 and
    >> XEON 5300 which both are Core based but also can take the XEON 5000
    >> series.
    >>
    >> XEON 5000 does Hyperthreading while XEON 5100 and 5300 do not...
    >>
    >> > I've install XP pro x64. No problem, windows sees my
    >> > processors..... but only uses one of them!
    >> > By default the bios had enabled Hyper threading and I could only use a
    >> > maximum of 12,5 % of my processor. Now that I have disabled HT, I can
    >> > use
    >> > 25%, but I can't find a way to use the whole power available.
    >> > I checked affinity and my main application is allowed to uses all the
    >> > processors....but it does not.
    >> > Any ideas ?

    >>
    >> How many cpus does the taskmanager show (set it to "one diagram per
    >> cpu"!)?
    >>
    >> And are you sure that your application (what application? Does it have a
    >> name?) is multithreaded and supports SMP? Just because its affinity can
    >> be to any of the logical processors doesn't mean it supports multiple
    >> processors.
    >>
    >> What you describe looks very much like an application that can't use
    >> multiple processors. If all CPUs are present in taskmanager then there
    >> is nothing wrong with your system or Windows...
    >>
    >> Benjamin
    >>
    Charlie Russel - MVP, Dec 21, 2006
    #4
  5. =?Utf-8?B?RXJpYyBBcHBlbG1hbnM=?=

    Guest

    On Thu, 21 Dec 2006 03:45:50 -0500, Charlie Russel - MVP
    <> wrote:

    > If Windows sees the processors, which it clearly does, then the
    > application itself is probably not written to use more than a single
    > processor. If this is the case, then turning off hyperthreading is
    > probably a good idea (actually it's probably a good idea anyway on a 4
    > core box that is used by a single person.)
    >


    Why is that?


    --
    Rock on!!!
    http://www.myspace.com/whistlertime
    , Dec 26, 2006
    #5
  6. Because Hyperthreading only emulates multiple processors, and there is
    overhead in the context switching required to do it. If the application
    isn't written to use multiple processors, then having hyperthreading on can
    actually make it slower, IME. Other situations it will still help, if you're
    doing enough other work to have the OS take advantage of the second
    "processor".

    --
    Charlie.
    http://msmvps.com/blogs/xperts64

    <> wrote in message
    news:eek:...
    > On Thu, 21 Dec 2006 03:45:50 -0500, Charlie Russel - MVP
    > <> wrote:
    >
    >> If Windows sees the processors, which it clearly does, then the
    >> application itself is probably not written to use more than a single
    >> processor. If this is the case, then turning off hyperthreading is
    >> probably a good idea (actually it's probably a good idea anyway on a 4
    >> core box that is used by a single person.)
    >>

    >
    > Why is that?
    >
    >
    > --
    > Rock on!!!
    > http://www.myspace.com/whistlertime
    Charlie Russel - MVP, Dec 27, 2006
    #6
  7. =?Utf-8?B?RXJpYyBBcHBlbG1hbnM=?=

    Guest

    On Wed, 27 Dec 2006 17:53:02 -0500, Charlie Russel - MVP
    <> wrote:

    > Because Hyperthreading only emulates multiple processors,


    This prompts me to ask (because I don't know) what happens when
    multiprocessors ARE present in the system and no emulation is needed?
    Doesn't that mean that emulation is ignored when multiple processors are
    present?

    I have a system with dual Opteron processors with windows 64 bit and yet
    to figure out if my system is anymore "smarter" or faster than a single
    processor unit.
    , Dec 31, 2006
    #7
  8. =?Utf-8?B?RXJpYyBBcHBlbG1hbnM=?=

    John Barnes Guest

    Windows splits up the tasks to take advantage of the two processors. And
    while some here joke about 2 slower speed processors not equaling the sum of
    the speeds, it is like electricity. You have parallel and serial
    connections depending on your desires. Serial and you have more volts, and
    parallel you have more amps. A dual core processor is capable of doing the
    sum of the speed of the two processors. Properly distributed work loads
    will in fact produce faster results on two slower speed processors than
    multiplexing the tasks on a single faster processor.


    <> wrote in message
    news:eek:...
    > On Wed, 27 Dec 2006 17:53:02 -0500, Charlie Russel - MVP
    > <> wrote:
    >
    >> Because Hyperthreading only emulates multiple processors,

    >
    > This prompts me to ask (because I don't know) what happens when
    > multiprocessors ARE present in the system and no emulation is needed?
    > Doesn't that mean that emulation is ignored when multiple processors are
    > present?
    >
    > I have a system with dual Opteron processors with windows 64 bit and yet
    > to figure out if my system is anymore "smarter" or faster than a single
    > processor unit.
    John Barnes, Jan 1, 2007
    #8
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