From owner-freebsd-chat  Fri Oct 27  8:21: 4 2000
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Date: Fri, 27 Oct 2000 17:20:06 +0200
From: Jamie Lokier <lk@tantalophile.demon.co.uk>
To: Alfred Perlstein <bright@wintelcom.net>
Cc: David Schwartz <davids@webmaster.com>,
	Jonathan Lemon <jlemon@flugsvamp.com>, chat@FreeBSD.ORG,
	linux-kernel@vger.kernel.org
Subject: Re: kqueue microbenchmark results
Message-ID: <20001027172006.A28504@pcep-jamie.cern.ch>
References: <20001025172702.B89038@prism.flugsvamp.com> <NCBBLIEPOCNJOAEKBEAKCEOPLHAA.davids@webmaster.com> <20001025161837.D28123@fw.wintelcom.net>
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Alfred Perlstein wrote:
> > If a programmer does not ever wish to block under any circumstances, it's
> > his obligation to communicate this desire to the implementation. Otherwise,
> > the implementation can block if it doesn't have data or an error available
> > at the instant 'read' is called, regardless of what it may have known or
> > done in the past.
> 
> Yes, and as you mentioned, it was _bugs_ in the operating system
> that did this.

Not for writes.  POLLOUT may be returned when the kernel thinks you have
enough memory to do a write, but someone else may allocate memory before
you call write().  Or does POLLOUT not work this way?

For read, you still want to declare the sockets non-blocking so your
code is robust on _other_ operating systems.  It's pretty straightforward.

-- Jamie


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