Re: [PATCH 0/4] add task handling notifier

[Christoph Hellwig <hch@infradead.org>]

On Thu, Dec 20, 2007 at 01:11:24PM +0000, Jan Beulich wrote:
> With more and more sub-systems/sub-components leaving their footprint
> in task handling functions, it seems reasonable to add notifiers that
> these components can use instead of having them all patch themselves
> directly into core files.

I agree that we probably want something like this.  As do some others,
so we already had a few a few attempts at similar things.  The first one
is from SGI and called PAGG (http://oss.sgi.com/projects/pagg/) and also
includes allocating per-task data for it's users.  Then also from SGI
there has been a simplified version called pnotify that's also available
from the website above.

Later Matt Helsley had something called "Task Watchers" which lwn has
an article on: http://lwn.net/Articles/208117/.

For some reason neither ever made a lot of progess (performance
problems?).

As said by other we really should have a register/unregister API instead
of exposing the implementation.  Also please don't export anything until
we actuall grow modular users in the tree.