Re: reiser4 and laptop_mode

[David Masover <ninja@slaphack.com>]

Sinitsyn Valentine wrote:
> Hi all,
> 
> I'm considering installing Reiser4 on my laptop, but I also want to
> use laptop_mode (http://www.xs4all.nl/~bsamwel/laptop_mode/index.html)
> to save battery power. So I'm wondering wether these two products are
> compatible with each other? I know that Reiser3 and ext3 did require
> special patches (now included in mainstream kernels) which schedule
> commits in a way which allows hard drive to spin down. I've looked
> through Google and this mailing list but didn't find any references to
> similar patches for Reiser4. Are they needed but nobody wrote them yet
> or is Reiser4 spindown-friendly just out of the box?

Reiser4 is spindown-friendly in one way -- until you run out of RAM, it
won't commit.  In fact, if you have enough RAM, you won't ever touch the
disk -- deleting a file before it's committed means it never touches disk.

It is not as spindown-friendly as laptop_mode, which notices when the
drive has to spin up anyway (maybe through a read) and flushes all
writes.  Don't know if they are compatible.