[frdmfghtr]

Is there a means to automatically turn one core on and off depending on CPU load and power status (i.e. AC or battery)? I can turn the second core on and off manually using CHUD, but I'd like to the processor at reduced speed/single core (something I miss from my iBook) when on battery power automatically, as I would like to improve the 3:30ish runtime on battery power.

[mduell]

The system automatically reduces the number of cores, clockrate, and cache size as appropriate for the current workload. Forcing it down to one core is only going to hurt performance without improving battery life. More details on Intel's SpeedStep technology here.

[frdmfghtr]

Thanks for the links. I looked around and all I could find was information regarding support for SpeedStep in Windows and Linux, nothing for OS X. In fact, there was not a mention of it on Apple's website, except for a couple of MacBook Pro technology overviews dated March 2006.

Apple - Support - Search Results

I don't see why this wouldn't be a user-configurable option, like it was on the PowerPC-based iBook.

[PeteC]

As far as I can tell, SpeedStep is implemented in hardware, with little to no OS interaction. And I remember seeing a discussion on SlashDot (which tends to have very knowledgeable posters) about how having two cores doing the work versus just one core is much more power efficient, so in this case its actually more effective to bump down the clockspeed of both cores rather than turn one off. Seems somewhat counter-intuitive, but it seemed to be a pretty generally accepted principal with the SlashDot crowd. Sorry I don't have the links for reference.

[mduell]

Originally Posted by frdmfghtr 

Thanks for the links. I looked around and all I could find was information regarding support for SpeedStep in Windows and Linux, nothing for OS X. In fact, there was not a mention of it on Apple's website, except for a couple of MacBook Pro technology overviews dated March 2006.

Apple - Support - Search Results

I don't see why this wouldn't be a user-configurable option, like it was on the PowerPC-based iBook.

As far as I know it doesn't require any OS support; if there are any apps for OSX that will display your clockrate in realtime you should be able to watch it change (I use Notebook Hardware Control in Windows). SpeedStep hasn't significantly changed since March 2006, so whatever is written about the MacBook Pro is still true for the current MBP and MB.

It's not a user-configurable option because there's nothing to choose. The system changes the three variables I mentioned earlier on the fly to minimize power usage while still maintaining performance.

What PeteC is alluding to is that two cores at 750Mhz consume less power than one core at 1.5Ghz (about half in theory), while doing the same amount of work (again, in theory; few things parallelize perfectly).

[frdmfghtr]

I'll try using CoreDuoTemp 1.0 - MacUpdate for a while and see what happens. Right away I can tell that something is happening, as the processor speed is ranging so far between 1.5 and 1.83 GHz.

(Can you tell I'm a stickler for these kinds of details?)

[mduell]

That's a pretty small range... it should drop <1Ghz at idle.

[frdmfghtr]

After running CoreDuoTemp for a while, I check its activity monitor, and it indicated that the lowest detected CPU speed to that point was 1.0 GHz. Although I wonder how much monitoring software like this affects the system it is monitoring.

[pra9ab0y]

all laptops notebooks do this. Its too save battery power. If you look the screen can sometimes dim if you are using both cores. You can change the way it manages battery and power but I dont know how yet!

[tinkered]

I am not sure why you would want it to be user configurable. That is like saying I wish my fuel-injection engine instead had a carborator I could tune myself.

My big concern would be that I get full performance while unplugged when I want it. I hardly care what my computer is doing while I am not looking, as long as it doesn't kill my battery in an hour. Besides, if you want it to idle at nothing, fold done your screen and send the processor to bed.

[frdmfghtr]

Originally Posted by tinkered 

My big concern would be that I get full performance while unplugged when I want it. I hardly care what my computer is doing while I am not looking, as long as it doesn't kill my battery in an hour. Besides, if you want it to idle at nothing, fold done your screen and send the processor to bed.

I'm the opposite; in AC power, it can be on automatic all it wants. When running on the battery, I want the processor to slow down, reduce power consumption, and stay there, whether I am using it or just looking at the screen.

Reading the screen is hard to do when the lid is closed

My late 2005 iBook G4 let me do this in the Energy Saver preferences; when on the power adapter, I selected "automatic" for the processor performance, and "reduced" for battery use. With a battery at 85 cycles, the reduced performance and low screen brightness translated to battery times of about 4-1/2 hours of actual use.

Earlier today when just looking at the screen on battery power, at one point the MacBook showed over 5 hours of battery life left; once I started to use it*, it jumped to about 3:30 left. Its that reduced power state I want it to stay in at all times on battery power; I don't need full processing power to edit documents or surf the web.

* Maybe it was the hard drive spinning back up...I couldn't tell.

[mduell]

Originally Posted by frdmfghtr 

Its that reduced power state I want it to stay in at all times on battery power; I don't need full processing power to edit documents or surf the web.

It's not giving you full processing power to edit documents and surf the web. It's only giving you as much processing power as you need to complete the task at hand.

[frdmfghtr]

I see that now--today while surfing wirelessly, I checked the processor temp using the iStat Pro widget--113F, where normally it is 140F. Apparently when I was monitoring it with CoreDuoTemp, the monitoring software was keeping the processor at a higher power state.