Multi-core support in Games?

Both Quake 4 and Call of Duty 2 now have SMP support, supposedly offering performance improvements on dual core and/or Hyper Threading enabled processors. 

For Call of Duty 2, you simply install the new patch and off you go; SMP support is enabled.  To verify, we ran our CoD 2 benchmark and kept a log of the total processor utilization over time.  Below is a shot of perfmon with a fresh install of CoD2 (sans SMP patch):

Note how the total CPU utilization for our dual-core testbed hovers right around 50%, with the maximum being just under 52% (the remaining 2% can be attributed to driver and other overhead that can eat up extra CPU cycles). 

Now, let's look at CoD2 CPU utilization with the SMP patch installed:

While the average CPU utilization only goes up by around 9%, the maximum CPU utilization increases tremendously, now up to 83%, showing us that the second core is being used. 

We looked at performance at 1024x768 and obviously the higher the resolution, the lesser the impact of a faster CPU (at the same time, the lower the resolution, the greater the impact will be as the game becomes less GPU limited). 

To ensure a fair comparison, we tested using the SMP patch and simply disabled SMP manually by setting the r_smp_backend variable to "0".  We confirmed that SMP support was actually disabled by running perfmon and measuring CPU utilization. 

 Call of Duty 2    SMP Disabled SMP Enabled
AMD Athlon 64 FX-57 (2.8GHz) 80.6 N/A
AMD Athlon 64 X2 4800+ (2.4GHz) 79.8 70.3
AMD Athlon 64 X2 3800+ (2.0GHz) 78.7 68.1
Intel Pentium Extreme Edition 955 (3.46GHz) 79.8 68.4
Intel Pentium Extreme Edition 840 (3.2GHz) 78.1 68
Intel Pentium D 820 (2.8GHz) 75.6 67.1

Surprisingly enough, we actually saw pretty large performance drops in CoD2 with SMP enabled across both AMD and Intel platforms.  This is unfortunate, but the withdrawn SMP support of Quake 3 makes it less than shocking. We do expect that things will get better as time goes on. 

Quake 4 was a different story; with r_useSMP enabled, we saw some extremely large performance gains with the move to dual core:

 Quake 4    SMP Disabled SMP Enabled
AMD Athlon 64 FX-57 (2.8GHz) 115.4 N/A
AMD Athlon 64 X2 4800+ (2.4GHz) 114.9 147.4
AMD Athlon 64 X2 3800+ (2.0GHz) 100.9 143.2
Intel Pentium Extreme Edition 955 (3.46GHz) 98.9 142.3
Intel Pentium Extreme Edition 840 (3.2GHz) 89.0 133.6
Intel Pentium D 820 (2.8GHz) 80.6 125.5

The SMP patch either only spawns two threads, or the instruction mix of Quake 4 with the patch does not mix well with Intel's Pentium EE 955.  The dual core with Hyper Threading enabled platform didn't do anything at all for performance. 

While we're only looking at two games, this is a start for multithreaded game development.  You can expect to see a lot of examples where dual-core does absolutely nothing for gaming, but as time goes on, the situation will change. 

Presler vs. Smithfield - A Brief Look Dual Core and Hyper Threading: Detriment or Not?
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  • Aenslead - Saturday, December 31, 2005 - link

    As J.J., from Spider-Man would say:

    "Ceap, crap, mega-crap!" and then toss it away.
  • ElJefe - Saturday, December 31, 2005 - link

    well it does move very fast in games. that is nice to see finally.

    it would be great if the overall power draw numbers were shown as on tomshardware. even there they showed a 90 watt difference between 4800 and the new 65nm. and that wasnt on the oc'd one. The oc'd one showed 150 more watts draw.
  • Viditor - Saturday, December 31, 2005 - link

    quote:

    well it does move very fast in games. that is nice to see finally

    Agreed...if it weren't for the X2, this would be an excellent chip by comparison!
  • Betwon - Friday, December 30, 2005 - link

    Now, anandtech begin to learn the truth. There are still many knowledge about CPU that anandtech need to learn.
    quote:

    . Through some extremely clever and effective engineering, Prescott actually wasn't any slower than its predecessors, despite the increase in pipeline stages.


    The resluts of tests are simple and clear, but the reasons are complex.

    In past years, anandtech took many mistakes about the correct reasons.
  • bldckstark - Monday, January 2, 2006 - link

    You do realize that none of this stuff is very important, right? Both chips work well. Nobody should be criticized for buying either one of them.
    I love my FIVE computers but making sure my wife and kids are healthy and happy is way more important than any electronic device, especially just one piece of it.
    Your damaging and hostile statements are making it appear as if you have forgotten this and the most important thing in the world is that you make all of us geeks think Anandtech is not perfect. News update - WE ALL KNOW THAT! We still like it.
  • bob4432 - Friday, December 30, 2005 - link

    why don't you do the gaming benchmark with bf2 fps unlocked? it appears that it is just hitting its built in lock with both the fx-57 and also P955 EE 3.46 cpus.
  • Spacecomber - Friday, December 30, 2005 - link

    I believe that they are using the timedemo feature of the game and that the frame rate max doesn't affect this. It would be nice to see more than just average frame rates reported for games, though. At least a range should be mentioned and maybe a standard deviation.

    Space
  • Betwon - Friday, December 30, 2005 - link

    We see a test, where the average fps of PD is less than (about 1% - 2%) the fps of AMD's. But PD's fps is more stable than AMD's.

    In the case that the average fps of netburst is better than the average fps of K8, the test shows that netburst is more stable than K8.
  • Betwon - Friday, December 30, 2005 - link

    The test isn't bf2.
  • bob4432 - Friday, December 30, 2005 - link

    any link you could give me on how to do the time demo from within bf2? is this new with the 1.12 patch?

    thanks

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