32bit apps on 64bit processor - any benefit?

Hi,

I've been reading up on the new ClawHammer processor, and I'm trying to get my head round what the benefits will be & what realistic performance increase there will be over, say, a 32bit Athlon. Can anyone post a summary of the main differences & improvements and what they will mean to a typical Desktop user?

For example, is it true that you will need a 64bit operating system or can you just run XP? Also are there any improvements running 32bit code on the Clawhammer?

Thanks,

Jim
7 answers Last reply
More about 32bit apps 64bit processor benefit
  1. If you're refering to the Hammer specifically, then yes, there will be quite a few improvements in all modes, not just 64-bit.
    1. There will be the integrated memory controller which would improve memory efficiency and latency significantly.
    2. An extra "packing" stage is added to increase scheduling efficiency so you'll have less blockage in the execution units.
    3. I'm not too sure on this one but I think in 64-bit mode, you will have 4 x86 decoders instead of the original 3.
    4. In 64-bit mode, there will be 16 general purpose registers vs 8 in normal mode. Even when running 32-bit code in this mode, performance should increase somewhat due to the extra registers.
    5. There will be 16 SSE/SSE2 registers as opposed to 8 in normal mode. This may help SSE/SSE2 operations.
    6. SSE2
    7. Higher clockspeeds.
    8. Possibly improved cache.

    There are probably more improvements but that's all I can list on the top of my head. What will this mean in terms of performance? Well, there will be an increase definitely but how much is anyone's guess.

    Quote:
    For example, is it true that you will need a 64bit operating system or can you just run XP? Also are there any improvements running 32bit code on the Clawhammer?


    Of that I'm aware, all instructions that need to be run in 64-bit mode can include an x86 prefix in front of the instruction switching the processor to 64-bit mode. This should be independent of the OS. So no, you don't need a 64-bit capable OS to use 64-bit applications. I'm not too sure on this part but I think that's true.

    "We are Microsoft, resistance is futile." - Bill Gates, 2015.
  2. Quote:
    So no, you don't need a 64-bit capable OS to use 64-bit applications. I'm not too sure on this part but I think that's true.

    Then what's the point of MS possibly already in dev, making WinXP x86-64?

    --
    When buying an AthlonXP, please make sure the bus is at 133MHZ, or you will get a lower speed!
  3. if AMD have built the chip so it would run 1 64bit or 2 32bit instructions, it would sure kick ass. But to do this is quite difficult to do.
  4. That's how it was first thought to be done, back in 2000, IIRC. Using a dual-in-one unit that activates two 32-bit operations per cycle. But in a way that'd be like splitting, it'd just waste time and often not give much really.

    In the end they just went for the simple 64-bit extensions.

    --
    When buying an AthlonXP, please make sure the bus is at 133MHZ, or you will get a lower speed!
  5. Ok, why aren't there more than 3 decoders on any x86 MPU? Because you really can't decode anymore than that. x86 is a very very *#$%#$ ISA. Extracting enough instructions to execute in parallel is a very hard job and in most cases, will not go above 3 instructions at once. So yes, you can make each execution unit be capable of doing 2 32-bit micro-ops per clock, but most of those units will remain idle anyway. It's not a simple matter of just adding more units.

    "We are Microsoft, resistance is futile." - Bill Gates, 2015.
  6. Hammer is mostly a 32 bit CPU.
    Itanium-2 is moving to a 32 bit precision 2X performance

    At the end i have speak with a horny lady
  7. Hammer is mostly a 32 bit CPU.
    Itanium-2 is moving to a 32 bit precision 2X performance

    At the end i have speak with a horny lady
Ask a new question

Read More

CPUs Apps Processors