On Sun, May 04, 2003 at 02:46:26AM -0700, Trent Piepho wrote:
> On Sun, 4 May 2003, Mark Mielke wrote:
> > Maybe, but probably not. Each ntserv process is likely limited to a time
> > slice of less than 0.1 seconds if it isn't calling system calls, and less
> Think about this, .1 seconds is 100 ms.  There are 16 players.  If four of
> those players use packet spam borgs and suck up 100 ms a piece, then that's
> 400 ms added to your lag.  Quite a bit.

They would only get 0.1 seconds if the ntserv process was doing pure CPU.

If it blocked on a system call at all, as would be expected from a
'packet spam' attempt, the process would be swapped out earlier. Also,
users of a recent version of the Alan Cox kernels benefit from the low
latency patches, as well as having the system scheduler update up to
1000 times a second instead of the traditional 100 times a second.

It simply isn't likely, unless you could come up with a way of causing
each packet you send to generate a substantial amount of CPU activity.
As it is, packets like "change direction to 34" are only a few bytes
long, take almost no time to process, and are not candidates for
'packet spamming'. If you are truly worried about one user sending so
many packets to the interface that they block up the interface on the
server side, I suppose this might be possible. However, they could do
the same thing with a SYN flood, or some other more effective method
than Netrek packets...

The most expensive packet operation I can think of for Netrek is
'request full update', and I believe that this request is throttled.
The second most expensive packet operation I can think of is the
message packet, as one message may result in messages being sent
to several clients. This request is also throttled.

So what packet would you use?


mark at mielke.cc/markm at ncf.ca/markm at nortelnetworks.com __________________________
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