On 02/03/06, Paul Querna <[EMAIL PROTECTED]> wrote:
This is part of a product that I am working on. Not all the platforms we run on have epoll() or kqueue(), so.....
-srp
Saju Pillai wrote:
>
>
> On 02/03/06, *Greg Ames* <[EMAIL PROTECTED]
> <mailto:[EMAIL PROTECTED]>> wrote:
>
> Paul Querna wrote:
>
> >> The event mpm expects the apr_pollset backends to be based on
> epoll()
> >> / kqueue() or Solaris 10 event ports. What are the reasons
> because of
> >> which poll() is not considered to be suitable for the event mpm ?
> >>
> >> Is this because of the large number of fd's to be polled and linear
> >> scalability that epoll() / kqueue() provides but poll() doesn't ? Is
> >> there any reason why a poll() based implemenation of event_mpm
> cannot
> >> be done if some performance degradation is ok ?
> >
> >
> > Performance is actually not the core reason.
> >
> > The core reason is the thread-safety of the pollset.
> >
> > Poll() does not allow a 'main thread' that is polling to get new
> sockets
> > added to it, without first waking it up.
> >
> > KQueue/EPoll both allow a second thread to insert pollfds into the
> > pollset, while a main thread is still polling. This significantly
> > reduces the complexity, and allows for better performance,
> because we
> > don't require a Context-Switch to add a client to the main pollset.
>
> Bill Stoddard and I originally used poll(). but there was a problem
> getting the event
> thread to notice a new descriptor and add it to the pollset in a
> timely manner. I added
> some Rube Goldberg stuff to solve that, involving a pipe and extra
> context switching as
> Paul mentioned. that was good enough for a proof of concept and
> shaking out other issues.
>
>
> Cool.
>
> Where can I see this code ? I looked through trunk & 2.2.x branches from
> the web but the oldest event.c uses epoll()/kqueue().
>
> I was looking to see if I could hack up a async worker like mpm using
> poll() on 2.0. A look at your code will help a lot :)
I don't want to be too discouraging, but why only using poll(), and why
only with 2.0?
This is part of a product that I am working on. Not all the platforms we run on have epoll() or kqueue(), so.....
-srp
They both seem like steps backwards :)
-Paul
