Re: Confused about power management

[Jukka Ruohonen <jruohonen%iki.fi@localhost>]

On Tue, Feb 15, 2011 at 09:25:10PM -0500, Stephen Krautheim wrote:
> I have also read the man page for "powerd", which seems be more related to
> hardware button behavior.

It is recommended that powerd(8) is always running (on x86 at least).
I don't know why it is not enabled by default.

> I have also read the Power Management page:
> http://www.netbsd.org/docs/power-mgmt/index.html, but this seems to talk
> about apm, which from other reading, seems to only be supported on i386,
> and although the man pages are included in my amd64 distro, the actual
> commands are nowhere to be found.

Forget that document if you are not running 1990s machines. (That page
should be probably removed, as outdated documentation is often worse than no
documentation at all.)

> What I would like is a behavior like this: If system idle & no disk
>       activity on exported disk for 15 min, then spin down
> drives and go to S1.
>       If S1 & ( drive activity requested from LAN  |  bus activity ) then go 
> to S0
> and spin up drives.

I believe we have no machinery for something as elegant as this. You can
manually spin down the disks with atactl(8) (cf. e.g. the powerd(8)'s
"acadapter" -script in /etc/powerd/scripts). But perhaps something like this
could be possible with some scripting...

> Something tells me that I may not be able to do quite this trick, as I think
> LAN activity alone is not enough to wake, which is OK (but not preferred)
> because I purposefully sought out a low power motherboard - but I at least
> would like to spin the drives down when not in use.

If by S1 you mean the "S1 sleep state" in ACPI jargon, that state is not
really supported in any operating system. On the other hand, if you mean
"suspend to RAM" (a.k.a. "S3 sleep state"), NetBSD does not unfortunately
yet support Wake-on-LAN functionality.

> I would have thought that some default behaviors would be built into the
> system that could be configured by a couple variable in rc.conf. 

Agreed. Power management is however under active development -- or to
rephrase that, NetBSD is still taking its first steps in this area.

- Jukka.