[Mldonkey-users] Upload/download tuning (was Re: only LowID-peers ??)

[mlist . mldonkey . users]

==> "cl" == Christian Loitsch <address@hidden> writes:

    sh> You have to dramatically increase max_clients_per_second. A
    sh> good value seems to be 20.
    >> That, and throttle the SYN packets coming in to your firewall
    >> to mldonkey.

    cl> I will try this.  Do you have any values?  I have ADSL
    cl> (512/128kbit/s)

Not really!  I'm trying to tune this as I go.  My connection
sustains about 1.5M/180.

I have max_clients_per_second set to 60, and the SYN filter set
to 20/s.  It has some effect, but not much.  It definitely improves
the interactive responsiveness, but I can't tell if I'm getting
better-quality connections.

Increasing max_clients_per_second and max_opened_connections to
astronomical values doesn't increase my active connection count
above 250 in any case.  This would make sense, if mldonkey is
correctly honoring the retry interval for queue checking.

You can test the effectiveness of the SYN protection by
shunting the packets first to a dummy chain that you can count
packets/bytes on.  Here is linux example:

  $ iptables ... --syn --limit 20/s --limit-burst 10 ACCEPT
  $ iptables ... --syn goto REJECT_FLOOD
  $ iptables ... ! --syn ACCEPT

The REJECT_FLOOD chain can just be empty:

  $ iptables -N REJECT_FLOOD

But you can count it periodically:

  $ iptables -nxvL REJECT_FLOOD

I don't know how much actual traffic is generated by a queue-check
action, but I turned down the SYN knob until I knew I was rejecting
a sizable percentage of new connections.

I'm still trying to increase the download reliability on rare/popular
files, so I'm also playing with max_sources_per_file, queued_timeout
and overnet_max_known_peers to increase the server's statefulness.

C