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The Final Answer
Authored by: ahbe on Dec 04, '03 12:40:22PM
Ok listen up, this should answer many of your questions. Here's my setup: 867Mhz 12" Powerbook OS X Panther 10.3.1 Xbench 1.1.3 I created a new account just for this test. This is mostly because my primary account has a bunch of stuff running in the background, and I wanted to make this as subjective as possible. So, after a fresh restart I logged into my newly created account and did a sysctl hw.cpufrequency and got back an answer of 533Mhz like everyone else. I ran Xbench on CPU test only and after several dozen tries, got an average of about 98.3 (It varies slightly). I than shutdown my powerbook, and reset the PMU. When I started it back up and logged into my special account and did a sysctl hw.cpufrequency test again, this time it said my CPU was running at 866MHz. Much better. I then ran Xbench again, and guess what. I got the EXACT same scores. Somewhere around 98.3. So, what does this tell me? sysctl doesn't tell you anything. Ignore it. In fact, just restarting my computer, not reseting the PMU, will give me different answers when I do a sysctl hw.cpufrequency. Sometimes I get 533MHz, sometimes I get 866MHz. So, at least on my 12" Powerbook, it doesn't matter. Any perceived speed increases are just in your head. Hope this helps. -- Ahbe

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The Final Answer
Authored by: dombi on Dec 04, '03 12:42:53PM

This is great, could someone else verify this as well?



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The Final Answer
Authored by: charlesb on Dec 04, '03 12:44:51PM

I confirm this. My Tibook 1 ghz was reporting 667 mhz from sysctl. I ran XBench, then reset PMU and reran XBench....same scores to within 0.5%. I conclude sysctl is just reporting wrong numbers....there is no performance change.



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The Final Answer
Authored by: Notch Johnson on Dec 07, '03 09:57:43AM

One more test I think would be informative:

1) Get your computer to a state where sysctl is displaying an incorrect value.

2) Run the benchtests or anything else that stresses the CPU, perhaps a dnet client with priority set to 0.

3) Immediately recheck the sysctl number.

This would tell if processor cycling is happening. The bench of CPU intensive app would elevate the clock speed to the maximum and rechecking sysctl should report a number that makes us happy.



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