Re: L4Mach or Refactor Hurd Servers?

[Ian Duggan]

> Personally, I find it very appealing to be able to perform *arbitrary*
> i/o or i/o-like operations by sending asyncronous messages, and then
> being able to wait on a collection of reply ports until one of the
> operations returns or times out. I guess one reason I like that way of
> operation is memories of the AmigaOS.

It's possible to do an IPC receive with a timeout (possibly indefinite)
with L4. It should be possible to mimic the described behavior using
this, no?

> Please keep in mind the case of calling select() or poll() on a few
> thousands of file descriptors, you want to support that without
> spawning an insane amount of threads.

IPCs will queue up in L4, won't they? You could have one thread
consuming the incoming IPCs. The synchronosity (is that word?) comes
from the senders blocking until the IPC returns.

I think you could do what you are describing using an indefinite IPC
receives in a loop that consume messages from your thousands of file
descriptors.

> BTW, how hard is it to implement something like Solaris "doors" on L4?
> If reconsidering the RPC-semantics, that might be an alternative worth
> investigating.

I'm unfamiliar with Doors. I found a few pages about an old "Doors on
Linux" implementation that was abandoned for "general lack of interest".
Where could I find more info on this?

-- Ian

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ian Duggan                    address@hidden
                              http://www.ianduggan.net