Date: Wed, 11 Feb 2004 18:48:47 +0100 From: Andre Oppermann <andre@freebsd.org> To: Mike Silbersack <silby@silby.com> Cc: freebsd-hackers@freebsd.org Subject: Re: select, sendto and ENOBUFS Message-ID: <402A6AFF.2020804@freebsd.org> In-Reply-To: <20040211030445.A1798@odysseus.silby.com> References: <20040210111013.G56192-100000@starbug.ugh.net.au> <20040211030445.A1798@odysseus.silby.com>
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Mike Silbersack wrote: > On Tue, 10 Feb 2004, Andrew wrote: > > >>The conclusion being that send, sendto and select will never block on a >>UDP socket and the man page just doesn't make it too clear. I'm assuming >>it is the same for raw sockets. >> >>UNPv1 section 6.3 seems to say that select should work for UDP...Part 2 >>under "Under What Conditions Is a Descriptor Ready" certainly indicates >>that select should work. >> >>Anyway a bug or not, is there a better work around than sleeping? I'm >>guessing not... >> >>Thanks, >> >>Andrew > > > Well, one workaround would be to figure out a way to have the kernel > implement the behavior you desire. :) > > I doubt that anyone will put effort into this problem soon; it looks like > it would be quite a large change to the network stack, and we all have > plenty of projects to work on. > > Maybe you could figure out where in the kernel the ENOBUFS is occuring, > and then add a tsleep which would be woken when the transmit queue cleared > a bit. That would introduce unexpected blocking, but I can't imagine that > waiting for a few packets to exit the queue would take much time. I traced it down when this topic came up the first time a couple of weeks ago. The ENOBUFS happens at the interface output queue when it is full. You better not put a tsleep in there. -- Andre
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