On 11/13/2013 11:24 AM, Garrett D'Amore wrote:
CPU power management is unlikely to do much for you. Its better to rely on C-states to save power on modern systems.
I'm not sure how to interpret that; the power.conf man page says that if cpu_deep_idle is enabled "On X86 systems this can translate to the use of ACPI C-States beyond C1", so it seems illumos is already using C states for CPU power management?
Frankly, very very few components on typical illumos based systems even support power management apart from the disk subsystem.
Probably only disks and CPU I would think, although it would be nice to be able to list out what the system thinks it could manage. I definitely don't want to spin down the disks, but I wouldn't mind saving a few watts here and there on the CPU. So maybe something like:
autopm disable autoS3 disable cpupm enable cpu_deep_idle enable
The display subsystem typically uses its own power management which doesn't participate with the rest of illumos' power management framework, IIRC.)
Unlike good old SPARC boxes, my x86 "headless" server has a graphics adapter in it. As I'm using a serial console, all it ever displays after boot is a blank screen, can't imagine it takes much power...
want, except to indicate "policy" -- modern devices (disk drives notwithstanding) can generally raise and lower power so quickly that its best to just let the drivers do their own power management explicitly, with only a few monitoring and policy hooks. This would lead to a vastly simpler power framework, which would probably be more likely to be taken up driver authors than the current mess.
I think that's where Linux is heading, the new Intel P-state driver for CPU power management doesn't really have any options, just turn it on and let it do its thing... They determined the previous ACPI driver actually ended up using more power by waking up the CPU to decide whether or not it should decrease the frequency than just letting the CPU deal with it itself internally.
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