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From "Stephen C. Tweedie" <...@redhat.com>
Subject Re: /dev/poll vs. aio_ (was: Re: Proposal: Get rid of most accept mutex)calls on hybrid server.)
Date Thu, 27 May 1999 05:17:00 GMT
Hi,

On Fri, 14 May 1999 14:44:08 +0000, Dan Kegel <dank@alumni.caltech.edu>
said:

> I have yet to use aio_ or F_SETSIG, but reading ready fd's from
> /dev/poll makes more sense to me than listening for realtime signals
> from aio_, which according to
> http://www.deja.com/getdoc.xp?AN=366163395 can overflow, in which case
> the kernel sends a SIGIO to say 'realtime signals overflowed, better
> do a full poll'.  

Yes.

> I'm contemplating writing a server that uses aio_; that case kind of
> defeats the purpose of using aio_, and handling it sounds annoying and
> suboptimal.

It adds code complexity but it shouldn't hurt the normal case: you don't
expect to get an overflow unless you have a _lot_ of traffic coming
through, in which case the cost of an occasional poll() to clear the
queue shouldn't make much odds.

However, it would be good to see real life profiling on this.

--Stephen

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