[linux-pm] Freezer: Don't count threads waiting for frozen filesystems.

[Matthew Garrett]

On Wed, Oct 29, 2008 at 04:37:30PM -0400, Alan Stern wrote:

> I discussed this last summer with Rafael.  It's a lot harder than it 
> looks, for all sorts of reasons.  For example, what about user tasks 
> that have access to memory-mapped I/O regions?

The only interesting cases of this I know of are X (which ought to stop 
doing so in the near future) and certain sound operations (which are 
going via a well-defined API anyway and need to handle devices going 
away at random, so not a problem). There may be some other niche cases, 
but really - if you're mmapping hardware then it's generally because you 
haven't written a proper kernel driver. Do that instead. Runtime power 
management's already going to make you wildly unhappy.

-- 
Matthew Garrett | mjg59 at srcf.ucam.org