Cores in a CPU, that is. Yes, at long last, after two years from when the first dual core CPUs (and nearly one year for quad cores) appeared on the market, we've now got games properly using the hardware that many gamers have these days. However, we've noticed on our forums that people are stating that some of the big names, such as the recent Crysis demo, are using all of the cores "fully". Read on to find out the truth behind this and what "fully" using all of the cores actually means.
To examine what's going on behind the scenes as a game is playing away, we ran Performance Monitor - Windows' built-in tool for analysing all kinds of usage figures. We'll explain how you can use it too, at the end of the news article, but to begin with, look at the following two images:
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3DMark03 - Battle of Proxycon
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To start with, a real blast from the past: Final Doom, running via Steam and a DOS emulator. The test system used a quad core CPU, so each line on the graph represents the % usage over time for each core. You can see that it's mostly using just the one core, the rest are almost certainly being used in background operations by the operating system, for the likes of Steam and the emulator. Next to that graph are the results for the Battle of Proxycon test from Futuremark's 3DMark03, running at a very high resolution with all kinds of AA, AF and shader effects on: here you can see this is definitely a "single core" test. Now let's look at Futuremark's most recent 3DMark title, 06, with the Return to Proxycon and CPU tests:
3DMark06 - Return to Proxycon
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The Return to Proxycon test is clearly up to "modern" standards because two cores are being heavily utilised (the funny drop is where the test ended) but take a look at the CPU test results - bang! All four cores, hammering away. Now ask yourself this: if this is what 100% fully used actually looks like, do I want my games to be the same? The answer is clearly "no" because you don't want the same levels of performance from 3DMark06's CPU Test in an actual game! The former is designed to be a total stress test; the latter is supposed to fun and playable. Bare in mind that the higher the usage, the more the performance of the game is going to be dependent on the CPU's speed - lower % figures either mean the graphics card is very busy and holding things up, or that the whole thing is a piece of cake for the CPU and graphics card (such as the Final Doom results above). With this in mind, now let's look at some other titles:
Call of Duty 4: Modern Warfare demo
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Unreal Tournament 3 beta demo
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In all cases, the maximum possible detail and graphics settings were used to ensure that the whole system is thoroughly stretched. BioShock is working the CPU pretty hard, across all of the available cores, but The Witcher isn't; Call of Duty 4 and Crysis are pretty similar, and the Unreal Tournament 3 deathmatch with 9 bots needs lots of CPU time. Not all new titles, though, grind away at every core: Rail Simulator seems to be using cores only when certain things happen, such as changing camera views and so on.
But notice that none of the testing games are using all four cores like the 3DMark06 CPU test - which is a good thing! (Edit: Just to clarify this bit, we're talking about workloads here. 3DMark06's CPU test seriously stresses all of the cores in a CPU - hence the constant 100% usage - which is exactly what you want from a benchmark with foresight, but not for games right at this moment in time.)
To use Performance Monitor yourself to check your system and games, use the following steps:
- Click on the Windows Start menu button and enter perfmon into the Run command.
- Windows XP users will start in the monitor immediately; Vista users must select it from the menu tree on the left.
- Click the Delete button several times to remove all of the counters that first load up.
- Then click Add, and select % Processor Time (Win XP) or Processor > % Processor Time (Win Vista).
- Click, drag and highlight the number of "instances" (i.e. cores) that you have: 0 = single core, 0+1 = dual core, 0+1+2+3 = quad core.
- Select Add, then Close/OK and away you go!
