On Fri, 21 Jan 2011 14:05:09 -0500, Dennis Nezic wrote:
> On Sat, 22 Jan 2011 07:59:32 +1300, Phillip Hutchings wrote:
> > 
> > On 22/01/2011, at 7:55 AM, Dennis Nezic wrote:
> > 
> > > On Fri, 21 Jan 2011 11:51:35 -0700, Ray Jones wrote:
> > >> 
> > >> If I understand correctly....
> > >> 
> > >> UDP has no such thing as flow control. So even though your
> > >> machine reads only X packets per second, the sending machine is
> > >> still sending and you're still receiving. If the packets build
> > >> up too far your machine will drop them, but you've already used
> > >> the bandwidth to get them there before they were dropped!
> > > 
> > > I agree it's a terrible waste -- but, I say, tough luck. Surely
> > > the senders will throttle back when they start seeing some of
> > > their packets not being acknowledged. (Like I said, we should
> > > avoid this situation as much as possible, but ultimately the user
> > > has to be in control. The network, selfish as this might sound,
> > > comes second!)
> > 
> > NO! We're using UDP - UDP packets have no acknowledgment. TCP would
> > behave like you describe, but UDP senders have no way of knowing
> > that there's a problem.
> > 
> > Freenet itself acknowledges packets,
> 
> That's what I was referring to.
> 
> > and that's part of the rate limiting, which obviously has some bugs.
> > Not reading the packets will work for a while, but when packets are
> > read and ack'd the senders will burst again, not knowing there's a
> > limit.
> 
> Sure they will know there is a limit -- they will know how long it
> took for the packets to get acked, and how many were dropped. It's not
> perfect, but I'm sure they will know enough to pull back when
> necessary.
> 
> > The only solution is to fix the limiter bugs, which is tough
> > for a project with so few developers.
> 
> Fixing that is definitely essential, although either way I think the
> user's limit has to be paramount. (Perhaps there are other ways to
> avoid dropping, like having the UDP packets queued into Freenet's
> memory, but not used more than XKiB/second -- so the long ack-ing
> works for a bit longer, rather than dropping the packets, which is
> worse.)

Bah. Ok, I see your point. The damage is already done when we are
flooded with traffic. There is no point hurting the user more by
dumping those already-arrived packets :b.
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