Dual core PM and games.

Posted:
in Current Mac Hardware edited January 2014
I am just starting to use my new 2.3 Dual Core PM and 30" ACD - I have upgraded from a 1st Gen iMac G5.



I have read in several places that most games on the Mac do not support both processors in a DP machine.



However, when I play Doom III and World of Warcraft in windowed mode and watch the CPU activity with Activity Monitor, both processors show intermittent activity (each to about 25% of max usage).



I wouldn't have thought OSX and background tasks would use any significant CPU resource, so is my system using both cores to run the games?



Is this something to do with the machine being a dual core, and not a dual processor machine?



-----The machine is a beast, by the way, and the display is stunning------

Comments

  • Reply 1 of 14
    powerdocpowerdoc Posts: 8,123member
    Doom 3 only use on CPU (may be the other is involved for the sound)

    Unreal 4 will use both CPU.
  • Reply 2 of 14
    messiahmessiah Posts: 1,689member
    Quote:

    Originally posted by Powerdoc

    Doom 3 only use on CPU (may be the other is involved for the sound)

    Unreal 4 will use both CPU.




    Is software that uses both processors able to distinguish between dual single core processors and a single dual core processor ? or is the difference completely transparent to the software?
  • Reply 3 of 14
    powerdocpowerdoc Posts: 8,123member
    Quote:

    Originally posted by Messiah

    Is software that uses both processors able to distinguish between dual single core processors and a single dual core processor ? or is the difference completely transparent to the software?



    It's totally transparent.

    BTW the difference is not that huge, read you optimize for both system the same way : multithreading.
  • Reply 4 of 14
    messiahmessiah Posts: 1,689member
    Quote:

    Originally posted by Powerdoc

    It's totally transparent.

    BTW the difference is not that huge, read you optimize for both system the same way : multithreading.




    Thanks for clearing that up!



  • Reply 5 of 14
    lundylundy Posts: 4,466member
    Quote:

    However, when I play Doom III and World of Warcraft in windowed mode and watch the CPU activity with Activity Monitor, both processors show intermittent activity (each to about 25% of max usage).



    I wouldn't have thought OSX and background tasks would use any significant CPU resource, so is my system using both cores to run the games?



    To understand this, run the game and quit all other applications (except Finder). Then open Activity Monitor, choose "all processes", make sure "# of threads" is selected to be shown in the View menu, and look at the number of threads that are in the system.



    The kernel can only pick a particular processor if there is a thread that can be put on it. There are plenty of threads available to be balanced across the 2 processors.



    Now assume that the game only has one thread. That means, in a simplified way, that the kernel could put that thread on one processor and all the other threads on the other. But it all depends on the overall workload and what the activity of the processors are at any given instant.



    Of course, if there are things the game is doing that do not depend on the results of each other's work, then it should have been written as separate threads so that they could be run on different processors. The kernel can't split a single thread over 2 processors - there is no way for it to tell how to do that.
  • Reply 6 of 14
    Thanks for the comprehensive response.

    I was suprised at how little processor resource was used by a DOOM 3, even when set on Ultra Quality and 1600 x 1200 - I only get a brief pause when I enter a new room, which must be down to loading (I am still using the stock 512 ram until my delivery comes from crucial).

    This game really must rely very heavily on the graphics card.
  • Reply 7 of 14
    >_>>_> Posts: 336member
    Quote:

    Originally posted by mattcl

    I have read in several places that most games on the Mac do not support both processors in a DP machine.



    I cannot speak for other games, but World of Warcraft only uses the second CPU for sound.



    - Xidius
  • Reply 8 of 14
    Quote:

    Originally posted by >_>

    I cannot speak for other games, but World of Warcraft only uses the second CPU for sound.



    - Xidius




    I find that very hard to believe. When I had a dual system, the load was evenly balanced between both processors. Now I have a quad system and each processor is getting about 25% utilization.
  • Reply 9 of 14
    Quote:

    Originally posted by mattcl

    Thanks for the comprehensive response.

    I was suprised at how little processor resource was used by a DOOM 3, even when set on Ultra Quality and 1600 x 1200 - I only get a brief pause when I enter a new room, which must be down to loading (I am still using the stock 512 ram until my delivery comes from crucial).

    This game really must rely very heavily on the graphics card.




    Out of interest, what graphics card did you order with your machine? I just ordered a Quad G5 with the 7800, so I'm curious to see how the graphics issues pan out.



    Cheers



    Neil
  • Reply 10 of 14
    I live in the UK - the 7800 is not available yet, so I got the standard 6600 with 256MB.



    So far no problems with games - I play DOOM 3 on highest settings, and get no slowdown now that I have upgraded to 2.5 gig RAM.



    WoW is set to full resloution, but I have to leave the glow effect off.



    HALO struggles at full resolution - C&C and AoM don't utilise the 30" resolutions fully, so they race along.



    I think the 30" screen is a big hill for the 6600 to climb, but it is coping with current games. I will upgrade in the summer if the 7800 is available as a user upgradeable option, and then the machine should last me 2 / 3 years.



    Matt.
  • Reply 11 of 14
    placeboplacebo Posts: 5,767member
    Quote:

    Originally posted by Powerdoc



    Unreal 4 will use both CPU.




    What the heck are you talking about?
  • Reply 12 of 14
    pbpb Posts: 4,248member
    Quote:

    Originally posted by Placebo

    What the heck are you talking about?



    He means probably Quake 4.
  • Reply 13 of 14
    Quote:

    Originally posted by mattcl

    I live in the UK - the 7800 is not available yet, so I got the standard 6600 with 256MB.



    So far no problems with games - I play DOOM 3 on highest settings, and get no slowdown now that I have upgraded to 2.5 gig RAM.



    WoW is set to full resloution, but I have to leave the glow effect off.



    HALO struggles at full resolution - C&C and AoM don't utilise the 30" resolutions fully, so they race along.



    I think the 30" screen is a big hill for the 6600 to climb, but it is coping with current games. I will upgrade in the summer if the 7800 is available as a user upgradeable option, and then the machine should last me 2 / 3 years.



    Matt.




    I'm only using a 23" display, plus I'll need more RAM. I decided to hold off so I could get more favourable prices. Can't wait to play Doom 3 though...



    Neil
  • Reply 14 of 14
    powerdocpowerdoc Posts: 8,123member
    Quote:

    Originally posted by PB

    He means probably Quake 4.



    Right and sorry for the confusion.
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