As of today, there is no scalable alternative to poll/select in the 2.5
kernel even though the topic has been discussed a number of times
before. The case for a scalable poll has been made often so I won't
get into that.

Attached is a port of the 2.4 async poll code to 2.5.41, written by
David Stevens with assistance from Jay Vosburgh and Mingming Cao (a
port for 2.5.42 is in progress and will be posted shortly). The
patch is a clean port of the 2.4 design and eliminates the use of
worktodos, just as Ben had done through the do_hack() function. The
patch has been tested on 2.5.41 using simple poll tests. A performance
evaluation and further testing is underway.

Even though Ben has indicated, on linux-aio and in OLS, that the 2.4
design doesn't scale well enough, it is a lot better than normal poll.
With the absence of alternatives and the impending feature freeze,
this patch would be one way to ensure that users have at least one
alternative to regular poll.

Ben, are you working on a different async poll implementation that is
likely to be ready by the feature freeze ?

Regards,
Shailabh