[lkml]   [2003]   [Jul]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: epoll vs stdin/stdout
On Mon, 7 Jul 2003, Eric Varsanyi wrote:

> On Mon, Jul 07, 2003 at 11:57:02AM -0700, Davide Libenzi wrote:
> > Events caught by epoll comes from a file* since that is the abstraction
> > the kernel handles. Events really happen on the file* and there's no way
> > if you dup()ing 1000 times a single fd, to say that events are for fd = 122.
> It is useful/mildly common at the app level to want to get read events
> for fd0 and write avail events for fd1. An app that might want to deal
> with reads from stdin in one process and writes to stdout in another
> (something like "team" perhaps) would have trouble here too.
> Epoll's API/impl is great as it is IMO, not suggesting need for change, I was
> hoping there was a good standard trick someone worked up to get around
> this specifc end case of stdin/stdout usually being dups but sometimes
> not. Porting my event system over to use epoll was easy/straightforward
> except for this one minor hitch.
> I considered:
> - using a second epoll object just for one of the fd's (to inspire
> delivery of the event to 2 wait queues in the kernel); a little
> ugly because of need to stack another epfd under the main one
> just for stdout write events
> - select() on (0, 1, epfd) and just use epoll with a timeout of 0
> when select fires to gather bulk of events; morally similar to
> previous but using select (which I want to just get away from)
> - make the app use stdin as its output (this is what I ended up doing);
> breaks redirection of stdout but that doesn't matter to this app

Any of the above. Pls wait for an incoming patch ...

- Davide

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:46    [W:0.114 / U:16.848 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site