[Pm-utils] Basic powersave hooks

[Richard Hughes]

On Fri, 2008-06-27 at 23:50 -0500, Victor Lowther wrote:
> After getting annoyed at fedora's lack of support for laptop-mode, I
> coded up a rudimentary set of hooks to enable/disable laptop mode,
> perform the VM and FS tweaking needed to make laptop mode effective, and
> enable/disable write caching and hard drive spindown.

DON'T DO THIS:
http://cgit.freedesktop.org/pm-utils/tree/pm/power.d/harddrive?h=powersave-hooks&id=ffe7052795e5ef8b64cb01c166e0993923e391af

Spinning down the drive like this is a _very_ quick way to kill a
desktop or server. Laptop drivers are (sometimes) designed for this, but
spinning down a server disk a few times per hour kills it after a few
months. There are must better heuristics to spin down a drive, and
ac/battery is not one of them. Using your hook would kill even a laptop
drive very quickly -- as Linux userspace has not yet been fixed not to
spin the disk up frequently it can easily hit the 5000-50000
spinup/spindown cycles in a year or so.

The other hooks look pretty sane on initial inspection, so the branch is
a step in the right direction. It's just the spindown hook I'm violently
opposed to.

Richard.