Re: [rfc] epoll interface change and glibc bits ...

[Dan Kegel <dank@kegel.com>]

Davide Libenzi wrote:
>>I'd be happy to contribute better doc... has the man page
>>for sys_epoll been written yet?
> 
> http://www.xmailserver.org/linux-patches/epoll.2
> http://www.xmailserver.org/linux-patches/epoll_create.2
> http://www.xmailserver.org/linux-patches/epoll_ctl.2
> http://www.xmailserver.org/linux-patches/epoll_wait.2
> 
> it is going to change though with the latest talks about the interface.

Hmm.  Right off the bat, I see a terminology problem.
The man page says

.SH NAME
epoll \- edge triggered asynchronous I/O facility

That's going to confuse some users.  They might think
epoll can actually initiate I/O.  Better to say

epoll \- edge triggered I/O readiness notification facility

Second, epoll_ctl(2) doesn't define the meaning of the
event mask.  It should give the allowed bits and define
their meanings.  If we use the traditional POLLIN etc, we
can say
   POLLIN - the fd has become ready for reading
   POLLOUT - the fd has become ready for writing
   Note: If epoll tells you e.g. POLLIN, it means that
            poll will tell you the same thing,
            since poll gives the current status,
            and epoll gives changes in status.

- Dan