Messages in this thread | | | Date | Wed, 06 Feb 2002 21:21:09 -0700 | From | Ben Greear <> | Subject | Re: want opinions on possible glitch in 2.4 network error reporting |
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Alan Cox wrote:
>>>That is correct UDP behaviour >>> >>This is totally untrue, unless the socket doing non-blocking I/O -- and >>even then you get -1 and EAGAIN from sendto. >> > > Not the case.
Are you claiming that you will never see -1 and EAGAIN on a nonblocking UDP socket with sendto? If so, I'll bet you a kernel patch that you are not correct (I get to write the patch and you include it :) )
> > >>there is no way to "lose" that data before it hits the wire, unless of >>course the network driver is broken and doesn't plug the upper layers when >>its TX queue is full. >> > > UDP is not flow controlled.
If it makes it through sendto, where can it be dropped before it hits the wire? I doubt the socket buffers are anthing other than FIFO, and the same goes for the ethernet/device queue. Since we (can) know at sendto whether or not the PDU was enqueued for transmit, it seems trivial to notify user space of success/failure of the local network stack, and I believe this is what is done.
Now granted, it can be dropped anywhere outside of the machine, but I can see no good reason to drop it inside the machine.
-- Ben Greear <greearb@candelatech.com> <Ben_Greear AT excite.com> President of Candela Technologies Inc http://www.candelatech.com ScryMUD: http://scry.wanfear.com http://scry.wanfear.com/~greear
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