Re: [patch, rfc] lt-epoll ( level triggered epoll ) ...

Davide Libenzi (davidel@xmailserver.org)
Tue, 11 Mar 2003 10:27:53 -0800 (PST)


On Tue, 11 Mar 2003, Jamie Lokier wrote:

> > LT epoll you simply use epoll_ctl(EPOLL_CTL_MOD) to switch between
> > EPOLLIN and EPOLLOUT.
>
> ?? Is this poorly worded? EPOLLIN and EPOLLOUT are independent events,
> aren't they?

Yes, they're. But since ET epoll has the edge feature that filter events,
you can safely register both events and insertion time *if you want*.

> > In front of this considerations we
> > have three options that I can think :
> >
> > 1) We leave epoll as is ( ET )
> > 2) We apply the patch that will make epoll LT
> > 3) We add a parameter to epoll_create() to fix the interface behaviour at
> > creation time ( small change on the current patch )
>
> Is it not better to (4) select the behaviour when an fd interest is
> registered? I think this is cleanest, if the code is not too
> horrible.

The code does not change much ( I think about 10 lines of code :) ), and
I'm for this option. That has also the other advantage to not change the
API parameters. Obviously man pages will have to be reviewed, but this is
another story :)

- Davide

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