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buggy CPU frequency-scaling on MacOs X?

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Hi all!

First of all, my RSS was propertly repared in the support-center in only one week, in Leon, Spain, so +1 point to apple, :). They changed the heatsink.

But, now I’m sad again with my new macbook. This week i have been testing my machine, and i have discovered the next:

1-When the battery is unplugged, the cpu frequency is ALWAYS at 1Ghz, independently of the system load. I use to unplug the battery when i’m at home for several days, so this sucks.

2- When the system is iddle, the cpu frequency NEVER down to 1Ghz, it’s always at 1.5Ghz, and rarely down to 1.33Ghz. This reduce the battery autonomy.

And THIS ISN’T NORMAL. In windows & linux it runs fine. So, has macosX a poor cpu frequency-scaling implementation?? or is only my macbook?? If the first, i hope apple fix this soon.

PD: I did the test’s with Menu Temperature (it’s free). CoreduoTemp shows the frequency incorretly under 10.4.8.

9 Responses to “buggy CPU frequency-scaling on MacOs X?”

  1. Benno Says:
    November 5th, 2006 at 1:12 am

    Can you give references (URLs) to the utilities you use to monitor the CPU frequency? (I am not (yet) very familiar with Mac OS X.) I can check the frequencies and report them here later.

    Cheers,

    – Benno

  2. naGt Says:
    November 5th, 2006 at 2:43 am

    Hi!!

    Just click in the “Menu Temperature” link in my post ; ). This is the software I use to monitor the cpu frequency. You can also use others like “hardware monitor”, but it’s not free.

    Try to avoid using “CoreDuoTemp” (allmost in 10.4.8). The version I tried didnt report correctly the cpu-frequency.

    Thanks for advance!!!

  3. Benno Says:
    November 5th, 2006 at 4:26 pm

    Hi,

    I installed both Menu Temperature and CoolBook and monitored the CPU stepping frequency.

    For Menu Temperature, I found the same values as you found. With battery in place, and running on batteries or with power adaptor, I see varying CPU frequency from 1.33 to 2.00 GHz, but its stationary CPU frequency mainly 1.5 GHz. With battery removed, I found that frequency was rock-steady 1 GHz. (Also with RSS test tool.)

    The results with CoolBook, the CPU frequency varied quite more. With batteries in place, and both running on batteries or with power adaptor, the CPU frequency varied from 1 GHz to 2 GHz, depending on the load. (Stationary frequency is 1 GHz, and 2 GHz for the RSS test tool). So there you see expected behavior, and Menu Temperature might give incorrect frequency indication.

    However, with batteries removed, the CoolBook utility also measured constantly 1GHz, even if I run the RSS test tool. I don’t understand why. It explains however, why MacBook owners suffering from RSS were able to keep their MacBook running with batteries removed! The CPU was running on 1 GHz at most, preventing the computer from running too hot.

    Maybe further searching for information on the mac forums?

    – Benno

  4. naGt Says:
    November 5th, 2006 at 6:47 pm

    ^_^!!!!

    I’m happy to see everything is running ok, thanks a lot Benno.

    MacOs X seems to scale the cpu fine, I will be able to sleep again :P .

    Now we only need to know why MacOsX’s developers decided to block the cpu frequency at 1Ghz when it has no battery. Any idea?

  5. Benno Says:
    November 5th, 2006 at 9:15 pm

    The 1GHz when it has no battery seems the be an OS X “feature”. It is documented by a MacBook user in detail.

    If the battery is not installed, “[effectively,] the CPU thinks that the temperature is unstable and automatically fixes your freq to 1Ghz.” See Apple Support Discussion for all the details.

    Bye,

    – Benno

  6. naGt Says:
    November 6th, 2006 at 12:22 am

    Hmmm, it seems a bug, in the Apple Support Discussion he said:

    ————–
    “Thermal trip indicator event is active. This indicates that the processor is above the recommended operating temperature. This bit is read-only and cleared once the temperature drops below recommended operating temperature”.

    Effectively, the CPU thinks that the temperature is unstable and automatically fixes your freq to 1Ghz.

    So this fix is definitely a result of a bug from Apple. My best guess is that they didn’t write the parameters inside the ACPI drivers to handle such an event since they don’t expect users to run their MacBook minus the battery.
    ——————

    I hope Apple fix this soon. I love my macbook, and this is the only “bug” or deffect I’ve found.

    Thanks

  7. Johan Says:
    November 8th, 2006 at 4:49 pm

    How about undervolting with coolbook? Will this give a cooler cpu that is more stable?

  8. naGt Says:
    November 8th, 2006 at 10:41 pm

    Hi Johan.

    The problem is not the temperature (in this case). The problem is that you can’t get all the power of your macbook when the batteries are unplugged (becouse the cpu frequency is ALLWAYS at 1GHz, independently of the system load).

    And, IMHO, working without batteries is very usual.

    APPLE, PLEASE, FIX THIS!!!

  9. Johan Says:
    November 9th, 2006 at 6:08 am

    Hello naGt,

    I have now experienced this first hand, as my battery died this morning. It got too empty, so it will not recharge. Now my MacBook runs @ 1GHz all the time. I can’t force it to run at a higher frequency with coolbook either.

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