I know of someone who has it working on RH AS 2.1. His report was that it sped up his i/o big time.

It may work on RHEL 3.0, but I've been working with support for a couple weeks on a TAR and have so far been unsuccessful to "alter database mount" without it hanging.

It's doing something.

output with async io disabled.

$ cat /proc/slabinfo | grep kio
kioctx 0 0 128 0 0 1 : 252 126
kiocb 0 0 96 0 0 1 : 252 126
kiobuf 0 0 64 0 0 1 : 252 126

output with async io enabled.

$ cat /proc/slabinfo | grep kio
kioctx 270 270 128 9 9 1 : 252 126
kiocb 66080 66080 96 1652 1652 1 : 252 126
kiobuf 236 236 64 4 4 1 : 252 126

-Ken