Re: epoll (was Re: [PATCH] async poll for 2.5)

From: Davide Libenzi (
Date: Wed Oct 23 2002 - 13:47:33 EST

On Wed, 23 Oct 2002, Benjamin LaHaise wrote:

> On Wed, Oct 23, 2002 at 09:49:54AM -0700, Dan Kegel wrote:
> > Furthermore, epoll is nice because it delivers one-shot readiness change
> > notification (I used to think that was a drawback, but coding
> > nonblocking OpenSSL apps has convinced me otherwise).
> > I may be confused, but I suspect the async poll being proposed by
> > Ben only delivers absolute readiness, not changes in readiness.
> >
> > I think epoll is worth having, even if Ben's AIO already handled
> > networking properly.
> That depends on how it compares to async read/write, which hasn't
> been looked into yet. The way the pipe code worked involved walking
> the page tables, which is still quite expensive for small data sizes.
> With the new code, the CPU's tlb will be used, which will make a big
> difference, especially for the case where only a single address space
> is in use on the system.

Ben, does it work at all currently read/write requests on sockets ? I
would like to test AIO on networking using my test http server, and I was
thinking about using poll() for async accept and AIO for read/write. The
poll() should be pretty fast because there's only one fd in the set and
the remaining code will use AIO for read/write. Might this work currently ?

- Davide

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