On Fri, 23 Jan 2004, Andre Oppermann wrote:
> Stuart Pook wrote: > >>send() for UDP should block if the socket is filled and the interface > >>can't drain the data fast enough. > > > > It doesn't (at least I cannot make it block) > > This stuff is rather complex. A send() on a UDP socket processes right > down to the if_output. If that fails because the ifqueue is full, the > packet will be free()d right away. No luck with blocking and retrying. > > >>Good question. There is not feedback loop like in tcp, so handling this > >>blocking and releasing would be a little bit harder to do for UDP. > > > > Send(2) indicates that it should do so. > > True. The only thing I can offer is that when one packet produces an > ENOBUFS, the socket will block on the next one for a couple of milliseconds. > Doing the full program requires significant changes to the current structure > of the BSD network code. > > You could do the same in userland with a call to nanosleep(2) when you get > a ENOBUFS. from memory that is what ping -f does.. > > >>>I have written a test program, > >>>http://www.infres.enst.fr/~pook/send/server.c, that shows that send does > >>>not block on FreeBSD. It does with Linux and Solaris. > >> > >>Do you know what the behaviour of Net- and/or OpenBSD is? > > > > NetBSD is the same as FreeBSD. I have not tested OpenBSD. > > MacOS X is similiar to FreeBSD in that send doesn't block, howver > > the send does not give an error: the packet is just thrown away. > > Browsing through the code I see that none of the BSDs are able to block > on an UDP send. > > -- > Andre > > _______________________________________________ > [EMAIL PROTECTED] mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "[EMAIL PROTECTED]" > _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
