Re: fs work - request structure

KevinL wrote:

> What I'm finding, tho, is that aufs keeps it's callback data in ctrl, whereas
> ufs keeps it in sio - and unless I can merge those somehow, the code cannot be
> nicely shared between them. What I'd like to do, ideally, is move the
> callback data out of ctrl into requestp. Are there any reasons I shouldn't do
> that?

The intermediary layer in aufs should be killed. There is no need for
three layers, at most two is needed. This has been on the todo for a
year or more, together with rewriting async-io to use macro operations
such as
  * Open file A and give me the first X KB of data, and close the file
if there is no more data.
  * Open file B and write these Y KB of data, then close the file if no
more data is expected.

This reasoning also applies to diskd.

Why: From a performance point of view IPC is a bad thing (being it over
shared memory, pipes, thread message queues or whatever), and having
many IPC calls for small related operations is not a very wise thing to
do. What we are interested in here is the data, we do not actually care
when the files are opened/closed, it is only a evil requirement for
beeing able to perform the data operations.

--
Henrik