Virtual PC 64 bit: how fast could it be?

Discussion in 'Misc' started by chibitul, Jun 29, 2003.

  1. chibitul

    chibitul Guest

    Hi,

    Suppose (it won't happen too soon since MS owns VPC now) that VPC is
    optimized for 64 bit architecture of G5. I am not talikng about
    emulating 64 bit Intel CPUs (Itanium, I think). Suppse you just want to
    emulate the 32 Pentium 4, but you write the code to use 64 bits on G5.

    How fast could it be???

    right now I would "guesstimate" (based more on feeling rather than
    benchmarks) that VPC 5 runs at about 300 MHz on my 900 MHz G3 iBook.

    Now would it be possible to get each G5 to emulate 2 P2 32-bit
    intructions in one cycle, so you actually get 4 instruction if you have
    a dual g5. How fast do you think VPC would be? Would you expect to
    compare it to a 2 GHz P4???

    Just wondering if you can emulate 2 32-bit instructions of P4 in one
    cycle of G5...

    Thanks
    chibitul, Jun 29, 2003
    #1
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  2. chibitul

    Thom Rosario Guest

    In article
    <>,
    chibitul <> wrote:

    > Hi,
    >
    > Suppose (it won't happen too soon since MS owns VPC now) that VPC is
    > optimized for 64 bit architecture of G5. I am not talikng about
    > emulating 64 bit Intel CPUs (Itanium, I think). Suppse you just want to
    > emulate the 32 Pentium 4, but you write the code to use 64 bits on G5.
    >
    > How fast could it be???
    >
    > right now I would "guesstimate" (based more on feeling rather than
    > benchmarks) that VPC 5 runs at about 300 MHz on my 900 MHz G3 iBook.
    >

    My 17" PowerBook G4 running Win XP in VPC6 reports itself as a 1.33 GHz
    Pentium, so I'm thinking 2 GHz should be a snap on a G5, even without
    any optimization.


    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    "We really haven't done everything we could to protect our
    customers ... Our products just aren't engineered for security."
    -- Brian Valentine, Sr VP in charge of MS Windows' Dev Team
    Thom Rosario, Jun 29, 2003
    #2
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  3. chibitul

    chibitul Guest

    In article <>,
    Thom Rosario <> wrote:

    > >
    > > right now I would "guesstimate" (based more on feeling rather than
    > > benchmarks) that VPC 5 runs at about 300 MHz on my 900 MHz G3 iBook.
    > >

    > My 17" PowerBook G4 running Win XP in VPC6 reports itself as a 1.33 GHz
    > Pentium, so I'm thinking 2 GHz should be a snap on a G5, even without
    > any optimization.


    Well, does it "feel" like a 1.33 GHz Pentium???
    chibitul, Jun 29, 2003
    #3
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    At 2003-06-29T14:24:31Z, chibitul <> writes:

    > Now would it be possible to get each G5 to emulate 2 P2 32-bit intructions
    > in one cycle, so you actually get 4 instruction if you have a dual g5.


    No. However, I *think* that the "G5" has more registers, so VPC's CPU
    emulation core could be re-compiled to store more temporary information in
    registers than RAM. Since registers are faster than even L1 cache and
    aren't subject to being flushed, that may speed up emulation.

    Out of curiosity, is VPC's CPU emulation multi-threaded? I haven't used it,
    but I sort of doubt it - and I can't imagine that it would be even remotely
    efficient it if did.
    - --
    Kirk Strauser
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    Kirk Strauser, Jun 30, 2003
    #4
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    At 2003-06-29T15:07:12Z, Thom Rosario <> writes:

    > My 17" PowerBook G4 running Win XP in VPC6 reports itself as a 1.33 GHz
    > Pentium,


    I used to run a VPC-alike program on my Amiga. I could configure it to
    report as a Pentium 200 or a 386 16, but the speed was identical in either
    case. The real question is: how fast does it truly run?

    > so I'm thinking 2 GHz should be a snap on a G5, even without any
    > optimization.


    Not a chance.
    - --
    Kirk Strauser
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    Kirk Strauser, Jun 30, 2003
    #5
  6. chibitul

    Thom Rosario Guest

    In article <>,
    Kirk Strauser <> wrote:

    > -----BEGIN PGP SIGNED MESSAGE-----
    > Hash: SHA1
    >
    > At 2003-06-29T15:07:12Z, Thom Rosario <> writes:
    >
    > > My 17" PowerBook G4 running Win XP in VPC6 reports itself as a 1.33 GHz
    > > Pentium,

    >
    > I used to run a VPC-alike program on my Amiga. I could configure it to
    > report as a Pentium 200 or a 386 16, but the speed was identical in either
    > case. The real question is: how fast does it truly run?
    >
    > > so I'm thinking 2 GHz should be a snap on a G5, even without any
    > > optimization.

    >
    > Not a chance.


    Have you used VPC on a G5? Or even a recent G4? It's quite impressive.


    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    "We really haven't done everything we could to protect our
    customers ... Our products just aren't engineered for security."
    -- Brian Valentine, Sr VP in charge of MS Windows' Dev Team
    Thom Rosario, Jun 30, 2003
    #6
  7. -----BEGIN PGP SIGNED MESSAGE-----
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    At 2003-06-30T13:19:04Z, Thom Rosario <> writes:

    >>> so I'm thinking 2 GHz should be a snap on a G5, even without any
    >>> optimization.


    >> Not a chance.


    > Have you used VPC on a G5? Or even a recent G4? It's quite impressive.


    No, I really haven't. I'm sure that it is very nice. However, it would
    have to be running at >100% efficiency to execute x86 code faster than a
    current-model x86 processor. I have no doubt that it's very usable, but I
    have severe doubts that it could outrun a 2 GHz Intel CPU when both are
    running Intel code.
    - --
    Kirk Strauser
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    Kirk Strauser, Jun 30, 2003
    #7
  8. chibitul

    Robert Guest

    You could 'compile' the x86 code into PPC code. That is take a
    segment of x86 code and produce a PPC shadow of the X86. That way
    instead of have to interpret the x86 code everytime it is run, you
    just run the x86 shadow.

    I do not know if VPC does this or not. MS would be in a good position
    to do things like this. To get really good performance out of VPC, MS
    could compile critical portions of Windows for the PPC, but M$ is not
    likely to do this.

    Robert
    Robert, Jul 2, 2003
    #8
  9. (Robert) writes:

    [x86->PPC code compilation]
    >I do not know if VPC does this or not.


    VPC does do a certain amount of JIT-style compilation on the x86 code,
    and caches it as well, which improves overall performance if you can stuff
    in more RAM and let it cache more of the system code.

    >MS would be in a good position
    >to do things like this. To get really good performance out of VPC, MS
    >could compile critical portions of Windows for the PPC, but M$ is not
    >likely to do this.


    MS is not likely to optimize VPC for the Mac at all. They would be loathe
    to encourage Windows growth on a platform they don't control well (look
    at how quickly they dropped PPC WinNT, thank goodness).

    --
    Cameron Kaiser * * posting with a Commodore 128
    personal page: http://www.armory.com/~spectre/
    ** Computer Workshops: games, productivity software and more for C64/128! **
    ** http://www.armory.com/~spectre/cwi/ **
    Cameron Kaiser, Jul 2, 2003
    #9
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