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I notice that when I play Minecraft, my CPU usage is only around 15 to 20 percent, at most. Is it possible to force my computer to allocate as much RAM, CPU time, etc. to the game, in order to get the best experience possible? Or, is the low CPU usage due to limitations in the JVM or the game code itself?

I have OptiFine installed, and I've already tried using renice to change the process priority and -Xmx to allocate more memory to Java. What else can I do?

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Is minecraft acting slow? What actual problem are you having? – Goddard Sep 5 '12 at 2:29
Nothing is actually "wrong", at least at the moment. I get 20-30 fps at the moment, which drops down to 12-15 when it's raining or snowing. But I'm thinking of trying some mods (like that could be more intensive. Really, I just want to know that I'm getting the best possible experience. – Keidax Sep 5 '12 at 2:50
up vote 3 down vote accepted

There's nothing in Linux which would force a program to use less than 100% CPU or not to allocate as much RAM as it needs, provided that no other process needs the same resources at the same time. nice value just determines how "nice" (got it?) the process plays with others and how much is it willing to share CPU time with other processes.

It's like if you're the only child in the playground you have all the toys to yourself, but if there are more then one, then nicer children give up more toys than those who are less nice...

Point is: it is likely the game is limited by your video card, not by CPU - that's why it's not using 100% of CPU, there's just no point. Playing with nice values is only going to make the game to run faster if you run some CPU-intensive calculations on the machine at the same time.

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Thank you for the explanation! – Keidax Sep 5 '12 at 3:04

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