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[Vista] power options> processor power mgt> MINIMUM processor st
It is more than obvious what "maximum processor state" does within this control panel applet. however, what the hell is a "minimum processor state"? i did my googling, and everyone has an answer for maximum, but no one could adequately explain what the MINIMUM state is supposed to do.
by default, both my "on battery/plugged in" settings have it set to "5%". this leads me to believe that "0%" is not the best setting. why would i always want a semi-active processor????
someone with intelligence please clarify!
Re: [Vista] power options> processor power mgt> MINIMUM processo
Well.. minimum is the opposite of maximum. If minimum is 5%, then that says it can't go below 5%.
Your processor should have several "ACPI P-states", different clock speeds to save power under low load or idle. Mine are 1800MHz(max speed)/1600MHz/800MHz. It won't be anything inbetween. Default minimum of 5% allows my laptop to clock down to the lowest speed of 800MHz, it can't run at 90MHz; if I set the minimum to 100%, it would always run at 1800MHz even if I am not doing anything CPU intensive. If I set it to 80%, it'd run at 1600MHz minimum.
I am sure your processor isn't capable of 0MHz while it's on, it will just go to the slowest P-state.. which should be a non-zero number.
not in ohio
|reply to AngryBlakMan |
said by AngryBlakMan:Because we call the state of 0% "being suspended" or "being switched off".
why would i always want a semi-active processor????
If the operating system is running, it needs a CPU to run on. If nothing else, there needs to be something running in order to be able to service further commands and crank the CPU up on demand. Click on the mouse? Then the OS gets an interrupt, which requires an active CPU to service it.
An idle system isn't doing nothing, anyway. If nothing else, it's taking a few hundred clock interrupts every second (I forget the current interrupt rate...).
the question begs to ask then, dave, why is this set to 5% instead of 1%? furthermore, if the system is never idle, why is this even a factor?
not in ohio
said by AngryBlakMan:The question is really "why is the scale marked in percentages at all?". Processors and chip sets don't have the ability to throttle themselves back to random speeds. The lowest this Pentium M will run is at 800 MHz, which is 40% of full clock. I think, but am not sure, that it can step in 200 MHz increments, i.e. 10% of full clock.
the question begs to ask then, dave, why is this set to 5% instead of 1%?
So, I suspect that the answer is that the UI is not processor specific, it has 5% increments to allow you to specify the general nature of what you want, and the processor management driver will find the nearest speed to the user's intention.
if the system is never idleI don't know what you mean by 'never idle'. My system is idle right now. It takes almost no CPU power at all to echo these keystrokes, so (a) the CPU spends over 99% of its time in the idle thread, and (b) the processor is running at its lowest supported clock speed.
When I hit 'post' I suppose the CPU clock rate will briefly increase, though probably not to maximum; a web posting will not take a lot of effort of anyone's part. The CPU will quickly drop back down to 800 MHz after that.
Maybe you were misled by my comment about servicing a few hundred interrupts a second. That is 'idle'; hardly anything to do.
But even without considering clock interrupts, the CPU is still executing. It just sits there executing in a tight loop in the OS doing nothing useful; that is what is meant by 'idle'. CPUs don't stop obeying instructions when idle any more than your brain stops when you're not doing anything. (Note to experts: I understand the HLT instruction )
But this is getting off the point. Over what range do you want to allow the OS to change the CPU speed?
For normal use, I can't see any reason for choosing the range as wide as possible. Minimum = the slowest the CPU will run. Maximum = full clock rate for the CPU. The latter will obviously be written as "100%" in anyone's idea of a UI, but the former could be written as whatever struck the UI engineer's fancy. It doesn't make ayy difference to the code actually controlling the processor; the processor won't go slower than it can go.