Dual Core chips?? - Hardware

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  1. Dual Core chips??

    Hello,

    I am seeing a lot of marketing of Dual Core systems. As you have
    guessed, I am not a hardware geek. What is the big advantage of dual
    core systems? I know it is like having 2 processors. Will each core
    perform at the high GigaHertz speeds that the marketers used in the past?

    I plan to buy a new PC sometime early next year. Does the current
    software technology take advantage of the dual core hardware? Is there
    significant performance speed on the system?

    Thank you in advance for any information.

    Regards,

    NJ

  2. Re: Dual Core chips??

    "Neil Jones" wrote in message
    news:UfD7h.29335$gN4.21614@newsfe14.lga...
    > Hello,
    >
    > I am seeing a lot of marketing of Dual Core systems. As you have
    > guessed, I am not a hardware geek. What is the big advantage of dual
    > core systems? I know it is like having 2 processors. Will each core
    > perform at the high GigaHertz speeds that the marketers used in the past?
    >
    > I plan to buy a new PC sometime early next year. Does the current
    > software technology take advantage of the dual core hardware? Is there
    > significant performance speed on the system?
    >
    > Thank you in advance for any information.
    >
    > Regards,
    > NJ


    Each core runs at the speed they were designed, 2GHz, 2.2GHz etc...
    If an application is not written to take advantage of dual core tech then
    a P4-3.2GHz will run that application faster than a dual core 2.4GHz
    given equal archs. However if the application is written to be dual
    core friendly then the 2.4GHz will beat the 3.2GHz single core machine.
    Gamers are typically the ones who adopt speed tech faster than the
    general public. Traditionaly games were single threaded but they are
    being converted over to take advantage of multi core systems. Getting
    more speed out of a single cpu by going multi core is easier at the
    moment for cpu makers because of the speed wall they have just hit.
    Eventually that speed wall will be overcome but until then putting more
    and more cores in a cpu is an easier way to make them faster and faster.
    There is another problem of scaling. Some system designs scale better
    than others. When you add more and more cpu's/cores to a system
    they all have to communicate together to get stuff done. That
    communication takes time and resources which slows the system down.
    A one cpu system works at X but a two cpu(core) system does not
    work at 2X, it is more like 1.8X. You loose a little in the communication.
    So a system with 80 cores in one cpu is not 80 times faster than a single
    core cpu. "They" say that we will have 80 core systems in just a few years.
    The Linux world has been multicore friendly for some time. The
    Windows world is just catching up. Some apps like rendering and ai and
    matrix math take full advantage of multicore while others like transaction
    processing systems not so much. Mainframes have being multicpu/multi
    core for decades. PeeCees are just catching up.

    Now your next question will/should be what is virtualization? That's
    another discussion.

    If you don't want to be obsoleted for a while the current system to purchase
    would be a dual cpu, dual core. hyperthreading, 64 bit system with
    virtualization. So far one can get that in x86-64, Itanium, Sparc and
    Power.
    x86-64 seams to be winning for the moment because of price.

    later,
    charles.....



  3. Re: Dual Core chips??

    Neil Jones wrote:

    > I am seeing a lot of marketing of Dual Core systems. As you have
    > guessed, I am not a hardware geek. What is the big advantage of dual
    > core systems? I know it is like having 2 processors. Will each core
    > perform at the high GigaHertz speeds that the marketers used in the past?


    Hello Neil,

    Your assumption is basically correct. There are two identical cores put in
    one silicon chip. Intel (nd AMD) gave up the Gigahertz race, because the
    high frequencies caused an over-proportional increase of electrical power
    required to run them. This was a slight problem for desktop PC's, because
    of cooling and noise issues and a huge problem for notebooks, because of
    battery drain. Therefore, Intel has revisited the lower frequency Pentium
    III core, giving it some bigger caches and updated it's architecture a
    little. Based on this architecture, the could put two CPU's on one die,
    without causing excessive power requirements. Shrinking the structures to
    65nm process also helped here. The result is a chip that is more powerful
    than the last Pentium 4, whilst more energy efficient.

    > I plan to buy a new PC sometime early next year. Does the current
    > software technology take advantage of the dual core hardware? Is there
    > significant performance speed on the system?


    Core 2 is well supported by Linux, since already the kernel 2.0 was SMP
    ready. Linux kernel will distribute the tasks over the available CPU's
    automatically. Please be aware that ONE SINGLE application running on Linux
    might not benefit from the two cores, as the kernel can only distribute
    tasks if there is more than one thing to do at a time. Your personal
    performance benefit from a Dual Core PC might therefore disappoint you.
    Anyway, the latest architectures, may it be Core 2 or AMD Athlon 64x2 give
    the average user more power than he usually needs.

    I hope this cleared it up a little...
    With regards,
    Hendric


    --
    Hendric Stattmann, Guntramsdorf, Austria. Registered Linux User #178879

  4. Re: Dual Core chips??

    On Sat, 18 Nov 2006 07:45:20 -0500, Neil Jones wrote:

    > Hello,
    >
    > I am seeing a lot of marketing of Dual Core systems. As you have
    > guessed, I am not a hardware geek. What is the big advantage of dual
    > core systems? I know it is like having 2 processors. Will each core
    > perform at the high GigaHertz speeds that the marketers used in the past?
    >
    > I plan to buy a new PC sometime early next year. Does the current
    > software technology take advantage of the dual core hardware? Is there
    > significant performance speed on the system?
    >
    > Thank you in advance for any information.
    >
    > Regards,
    >
    > NJ


    The others have done a good job of covering the technical aspects. Just
    let me add that whether you will see any gain or not depends a lot on what
    you do. I've read that a dual core processor does not real run as fast as
    a two cpu system - it gives the equivalent of about 1.6 processors. If you
    run a bunch of small jobs at the same time - you'd see an improvement. If
    you typically run one cpu hungry job at a time and it is not written to be
    multithreaded, then a dual core system will run no faster than a single
    core of the same speed. Most processes are not written to be
    multithreaded. Optimization for multiple processors is a very difficult
    task.


  5. Re: Dual Core chips??

    In article ,
    ray@zianet.com says...
    > On Sat, 18 Nov 2006 07:45:20 -0500, Neil Jones wrote:
    >
    > > Hello,
    > >
    > > I am seeing a lot of marketing of Dual Core systems. As you have
    > > guessed, I am not a hardware geek. What is the big advantage of dual
    > > core systems? I know it is like having 2 processors. Will each core
    > > perform at the high GigaHertz speeds that the marketers used in the past?
    > >
    > > I plan to buy a new PC sometime early next year. Does the current
    > > software technology take advantage of the dual core hardware? Is there
    > > significant performance speed on the system?
    > >
    > > Thank you in advance for any information.
    > >
    > > Regards,
    > >
    > > NJ

    >
    > The others have done a good job of covering the technical aspects. Just
    > let me add that whether you will see any gain or not depends a lot on what
    > you do. I've read that a dual core processor does not real run as fast as
    > a two cpu system - it gives the equivalent of about 1.6 processors.


    A dual core system *IS* a two CPU system.

    > If you
    > run a bunch of small jobs at the same time - you'd see an improvement. If
    > you typically run one cpu hungry job at a time and it is not written to be
    > multithreaded, then a dual core system will run no faster than a single
    > core of the same speed. Most processes are not written to be
    > multithreaded. Optimization for multiple processors is a very difficult
    > task.


    Windows (and Linux) run many threads at a time. Dual cores will
    help some in any case. With a dual processor/core system if one CPU
    hog is running the system will still be responsive. A single CPU
    system may be brought to its knees.

    However, to get any benefit out of a dual core system, make sure it
    has enough memory and fast disks (plural, preferable). If they get
    in the way, the second processor is going to do nothing for
    performance.

    --
    Keith


  6. Re: Dual Core chips??


    > work at 2X, it is more like 1.8X. You loose a little in the communication.
    > So a system with 80 cores in one cpu is not 80 times faster than a single
    > core cpu. "They" say that we will have 80 core systems in just a few years.


    80X core would be a huge win for graphics on Linux since there is no
    sight of open sourcing
    of ATI and Nvidia graphics. It won't put high end gfx cards on the
    shelf, but
    it will probably blow the low end and midrange out of the water.
    How affordable that performance would be in the long run remains to be
    seen.
    Nvidia and ATI are way ahead of Intel and it's probably way cheaper to
    produce a
    chip with 96 or 128 specialized lean and trim cores than fat x86 cores.
    Maybe they can make X4000 based on their sucky ia64 :-]
    Intel does not seem to be cutting corners and adding any questionable
    code in their
    2d/3d drivers to get a lead on the competitors. Hence X3000 being 2x
    slower than 6200
    that is ancient news in itself.
    But I think in a long run Intel *will* put ATI and Nvidia out of
    business if SGI
    lawyers won't.


  7. Re: Dual Core chips??

    On Sat, 18 Nov 2006 07:45:20 -0500, Neil Jones
    wrote:

    >Hello,
    >
    >I am seeing a lot of marketing of Dual Core systems. As you have
    >guessed, I am not a hardware geek. What is the big advantage of dual
    >core systems? I know it is like having 2 processors. Will each core
    >perform at the high GigaHertz speeds that the marketers used in the past?


    The umm, big advantage of dual core is that it gives CPU mfrs something to
    do with the additional chip real-estate as they go to smaller and smaller
    IC geometries:-)... a bit cynical but there's nowhere else to go at
    present. The clock speed ramp is tapped out until some potential
    fundamental material science breakthrough - it'll likely climb a bit but
    more slowly than historically.

    There are differences between Intel & AMD's approach but it *is* like have
    two processors... but since they're on the same chip, they share the same
    memory bus. In the worst case, if you had two tasks with very high memory
    bandwidth requirements, they'd probably run in shorter time if run
    consecutively than if run concurrently. In the best case you can run two
    fairly compute/memory intensive tasks efficiently or have one moderately
    intensive task and also have the system still respond to user inputs for
    another less intensive task.

    Current dual core chips are backed off on clock speed slightly from what
    can be done with a single core but not by much... and not enough where
    you'd regret getting the dual vs. the "faster" single-core.

    I have a single core system at home and a dual-core of the same clock speed
    and memory bandwidth at work and the difference in response is noticeable -
    with dual cores you see much less of the hour glass when trying to do two
    things at once.

    >I plan to buy a new PC sometime early next year. Does the current
    >software technology take advantage of the dual core hardware? Is there
    >significant performance speed on the system?


    I think the best one can say at the moment for the software is that "it's
    getting there". Ideally we'd have tasks with multiple threads of execution
    which could run entirely simultaneously for a tangible benefit but that'd
    be rare for most common tasks and then if we had err, quad-cores we could
    run two dual-threaded tasks simultaneously without suspending one task
    while the other runs. I have my doubts that anyone's going to realize any
    real benefits of quad-core CPUs for a while... at least on the desktop.

    Game makers are curently working on multi-threading their CPU work-load -
    they have to for the most recent game consoles anyway so there's some
    fallout there for the PC desktop. I'm not a gamer so don't follow it
    closely but maybe someone else can comment.

    The bottom line is that yes, it's worth getting the dual-core system even
    now, especially given the price-point vs. single core. If you assume some
    reasonable gain in software redesign and coding you come out ahead vs.
    single core. My crystal ball says that a CPU bought now could have a
    relatively long life-cycle before you'd even be tempted to look for
    something better... but I've never been much good at reading crystal balls.

    --
    Rgds, George Macdonald

  8. Re: Dual Core chips??

    On Sat, 18 Nov 2006 14:07:34 GMT, "***** charles"
    wrote:

    >If you don't want to be obsoleted for a while the current system to purchase
    >would be a dual cpu, dual core. hyperthreading, 64 bit system with
    >virtualization. So far one can get that in x86-64, Itanium, Sparc and
    >Power.


    Just drop the hyperthreading idea - the current top performers, Core 2 Duo
    and Athlon64 X2, do not have it.

    --
    Rgds, George Macdonald

  9. Re: Dual Core chips??

    On Sat, 18 Nov 2006 12:56:27 -0500, krw wrote:

    > In article ,
    > ray@zianet.com says...
    >> On Sat, 18 Nov 2006 07:45:20 -0500, Neil Jones wrote:
    >>
    >> > Hello,
    >> >
    >> > I am seeing a lot of marketing of Dual Core systems. As you have
    >> > guessed, I am not a hardware geek. What is the big advantage of dual
    >> > core systems? I know it is like having 2 processors. Will each core
    >> > perform at the high GigaHertz speeds that the marketers used in the past?
    >> >
    >> > I plan to buy a new PC sometime early next year. Does the current
    >> > software technology take advantage of the dual core hardware? Is there
    >> > significant performance speed on the system?
    >> >
    >> > Thank you in advance for any information.
    >> >
    >> > Regards,
    >> >
    >> > NJ

    >>
    >> The others have done a good job of covering the technical aspects. Just
    >> let me add that whether you will see any gain or not depends a lot on what
    >> you do. I've read that a dual core processor does not real run as fast as
    >> a two cpu system - it gives the equivalent of about 1.6 processors.

    >
    > A dual core system *IS* a two CPU system.


    It is and it ain't. It is still not as efficient as two cpus on two
    different chips - there are some shared resources that slow things down.

    >
    >> If you
    >> run a bunch of small jobs at the same time - you'd see an improvement. If
    >> you typically run one cpu hungry job at a time and it is not written to be
    >> multithreaded, then a dual core system will run no faster than a single
    >> core of the same speed. Most processes are not written to be
    >> multithreaded. Optimization for multiple processors is a very difficult
    >> task.

    >
    > Windows (and Linux) run many threads at a time. Dual cores will
    > help some in any case. With a dual processor/core system if one CPU
    > hog is running the system will still be responsive. A single CPU
    > system may be brought to its knees.
    >
    > However, to get any benefit out of a dual core system, make sure it
    > has enough memory and fast disks (plural, preferable). If they get
    > in the way, the second processor is going to do nothing for
    > performance.



  10. Re: Dual Core chips??

    On Sat, 18 Nov 2006 21:13:00 -0700, ray wrote:

    >On Sat, 18 Nov 2006 12:56:27 -0500, krw wrote:
    >
    >> A dual core system *IS* a two CPU system.

    >
    >It is and it ain't. It is still not as efficient as two cpus on two
    >different chips - there are some shared resources that slow things down.


    For instance?

  11. Re: Dual Core chips??

    On Sat, 18 Nov 2006 23:18:17 -0500, daytripper wrote:

    >>> A dual core system *IS* a two CPU system.

    >>
    >>It is and it ain't. It is still not as efficient as two cpus on two
    >>different chips - there are some shared resources that slow things down.

    >
    > For instance?

    I haven't actually met the difference with an smp system in real life
    applications. However, unlike smp, multiple cores share the same memory
    bus. That's the reason why of their huge L2.

  12. Re: Dual Core chips??

    On Sun, 19 Nov 2006 17:16:42 GMT, PdL wrote:

    >On Sat, 18 Nov 2006 23:18:17 -0500, daytripper wrote:
    >
    >>>> A dual core system *IS* a two CPU system.
    >>>
    >>>It is and it ain't. It is still not as efficient as two cpus on two
    >>>different chips - there are some shared resources that slow things down.

    >>
    >> For instance?

    >I haven't actually met the difference with an smp system in real life
    >applications. However, unlike smp, multiple cores share the same memory
    >bus. That's the reason why of their huge L2.


    But....every Intel x32 multi-processor platform shares the same *memory bus* -
    whether it uses a multi-dropped "front side bus" or separate pipes to the
    shared memory controller.

    A memory reference made by any processor - or any core within - has to undergo
    the same coherency checks regardless of cache organization/distribution - and
    if it misses it still resolves to the same ranks of ram.

    There's no functional difference if the platform is a single socket multicore
    or a multi-socket single core. Coherency traffic happens. And, ultimately, the
    real throughput choke point is shared - at the dimms - regardless of
    processor/core topology.

    Thus, I fail to see a distinction that actually matters. And if you happen to
    see a copy of the latest Clovertown benchmarks, I doubt you'll disagree...

    Cheers

    /daytripper

  13. Re: Dual Core chips??

    daytripper wrote:
    >
    > There's no functional difference if the platform is a single socket multicore
    > or a multi-socket single core. Coherency traffic happens. And, ultimately, the
    > real throughput choke point is shared - at the dimms - regardless of
    > processor/core topology.
    >


    On the subject of coherency, I quickly become incoherent.

    If processors actually share L2 then why isn't it possible for closely
    cooperating threads to use the same data without touching main memory,
    or without being held up waiting for main memory?

    I seriously doubt if anyone will go to the trouble to do this, since
    people have a hard enough time writing correct multi-threaded code
    without worrying over such niceties, but there are some latency-hiding
    tricks one might be tempted to try with two closely-cooperating threads
    (lots of stuff in the literature).

    Robert.


  14. Re: Dual Core chips??

    In article <1163971214.790271.219750@m73g2000cwd.googlegroups. com>,
    rbmyersusa@gmail.com says...
    > daytripper wrote:
    > >
    > > There's no functional difference if the platform is a single socket multicore
    > > or a multi-socket single core. Coherency traffic happens. And, ultimately, the
    > > real throughput choke point is shared - at the dimms - regardless of
    > > processor/core topology.
    > >

    >
    > On the subject of coherency, I quickly become incoherent.
    >
    > If processors actually share L2 then why isn't it possible for closely
    > cooperating threads to use the same data without touching main memory,
    > or without being held up waiting for main memory?


    That's certainly a possibility, but it's a architecture trade-off.
    Not sharing L2s is good for performance when they have little
    common data.

    > I seriously doubt if anyone will go to the trouble to do this, since
    > people have a hard enough time writing correct multi-threaded code
    > without worrying over such niceties, but there are some latency-hiding
    > tricks one might be tempted to try with two closely-cooperating threads
    > (lots of stuff in the literature).


    I think you're right, though the concept of "helper threads" isn't
    new. In fact this is what prefetching hardware (and software
    hinting) tries to do.

    --
    Keith

  15. Re: Dual Core chips??

    George Macdonald wrote:

    > Current dual core chips are backed off on clock speed slightly from
    > what can be done with a single core but not by much... and not enough
    > where you'd regret getting the dual vs. the "faster" single-core.
    >


    Only on Intel systems.

    AMD won the performance crown over many years because it threw out the
    'more cpu cycles, the faster the processor' dogma of previous
    architectures. It developed more efficient processors that did more per
    cycle and so its cpus preformed much better and ran a lot cooler than
    Intel's electric heaters. Its dual-cores were/are exactly the same as
    the signle core equivalents.

    Now that Intel has taken this onboard and released some very efficient
    processors which run with slower clock cycles than the previous
    pentiums (pentium Ms excluded) it has regained the performance crown
    after many years of playing second fiddle to AMD.

  16. Re: Dual Core chips??

    George Macdonald wrote:

    > Just drop the hyperthreading idea - the current top performers, Core 2
    > Duo and Athlon64 X2, do not have it.
    >


    And don't need it.

    HT was just a kludge by Intel to try and squeeze some more performance
    (and marketting collateral) out of the P4 when it realised that the
    net-burst architecture was not working as well as they had hoped. For
    some applications HT actually slowed things down.

  17. Re: Dual Core chips??

    "krw" wrote in message
    news:MPG.1fcae68c3b0bb31989c00@news.individual.net ...
    > In article <1163971214.790271.219750@m73g2000cwd.googlegroups. com>,
    > rbmyersusa@gmail.com says...

    , I quickly become incoherent.
    > >
    > > If processors actually share L2 then why isn't it possible for closely
    > > cooperating threads to use the same data without touching main memory,
    > > or without being held up waiting for main memory?

    >
    > That's certainly a possibility, but it's a architecture trade-off.
    > Not sharing L2s is good for performance when they have little
    > common data.
    >
    > > I seriously doubt if anyone will go to the trouble to do this, since
    > > people have a hard enough time writing correct multi-threaded code
    > > without worrying over such niceties, but there are some latency-hiding
    > > tricks one might be tempted to try with two closely-cooperating threads
    > > (lots of stuff in the literature).

    >
    > I think you're right, though the concept of "helper threads" isn't
    > new. In fact this is what prefetching hardware (and software
    > hinting) tries to do.


    If the caches are shared, and the data is in the cache for CPU1, then CPU2
    can most certainly access it. This is automatic and requires no special
    programming. I get the impression that Myers wants to do special
    programming to make it possible to share what's already available! Or am I
    making a really dumb mistake? ;-)



  18. Re: Dual Core chips??

    On Mon, 20 Nov 2006 11:24:46 +0000, Chris wrote:

    >George Macdonald wrote:
    >
    >> Just drop the hyperthreading idea - the current top performers, Core 2
    >> Duo and Athlon64 X2, do not have it.
    >>

    >
    >And don't need it.
    >
    >HT was just a kludge by Intel to try and squeeze some more performance
    >(and marketting collateral) out of the P4 when it realised that the
    >net-burst architecture was not working as well as they had hoped. For
    >some applications HT actually slowed things down.


    To some extent all true *but* you will get argument on the "kludge" from
    some... and Intel has not ruled out HT for future product AIUI.

    --
    Rgds, George Macdonald

  19. Re: Dual Core chips??

    On Mon, 20 Nov 2006 11:16:29 +0000, Chris wrote:

    >George Macdonald wrote:
    >
    >> Current dual core chips are backed off on clock speed slightly from
    >> what can be done with a single core but not by much... and not enough
    >> where you'd regret getting the dual vs. the "faster" single-core.
    >>

    >
    >Only on Intel systems.
    >
    >AMD won the performance crown over many years because it threw out the
    >'more cpu cycles, the faster the processor' dogma of previous
    >architectures. It developed more efficient processors that did more per
    >cycle and so its cpus preformed much better and ran a lot cooler than
    >Intel's electric heaters. Its dual-cores were/are exactly the same as
    >the signle core equivalents.


    I believe it was AMD's intention to sell backed off dual cores - they said
    so back before C2D came along to put a wrench in the works, and initial
    product was so aligned. C2D plus price pressure forced them to a different
    path, though I believe the top MHz AMD64 is still a single core CPU.

    >Now that Intel has taken this onboard and released some very efficient
    >processors which run with slower clock cycles than the previous
    >pentiums (pentium Ms excluded) it has regained the performance crown
    >after many years of playing second fiddle to AMD.


    But did they really?... play "second fiddle"?:-) I think only to the
    cognoscenti - amazing what FUD, Mikey & Co. and guys in blue bunny suits
    will do:-)

    --
    Rgds, George Macdonald

  20. Re: Dual Core chips??

    In article ,
    fnsfmf@jps.net says...
    > "krw" wrote in message
    > news:MPG.1fcae68c3b0bb31989c00@news.individual.net ...
    > > In article <1163971214.790271.219750@m73g2000cwd.googlegroups. com>,
    > > rbmyersusa@gmail.com says...

    > , I quickly become incoherent.
    > > >
    > > > If processors actually share L2 then why isn't it possible for closely
    > > > cooperating threads to use the same data without touching main memory,
    > > > or without being held up waiting for main memory?

    > >
    > > That's certainly a possibility, but it's a architecture trade-off.
    > > Not sharing L2s is good for performance when they have little
    > > common data.
    > >
    > > > I seriously doubt if anyone will go to the trouble to do this, since
    > > > people have a hard enough time writing correct multi-threaded code
    > > > without worrying over such niceties, but there are some latency-hiding
    > > > tricks one might be tempted to try with two closely-cooperating threads
    > > > (lots of stuff in the literature).

    > >
    > > I think you're right, though the concept of "helper threads" isn't
    > > new. In fact this is what prefetching hardware (and software
    > > hinting) tries to do.

    >
    > If the caches are shared, and the data is in the cache for CPU1, then CPU2
    > can most certainly access it. This is automatic and requires no special
    > programming. I get the impression that Myers wants to do special
    > programming to make it possible to share what's already available! Or am I
    > making a really dumb mistake? ;-)
    >
    >
    >


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