[Opensim-dev] Does OpenSim need to leave so many packets marked as reliable?

[Melanie]

Hi again,

there may be some object updates that can be sent unreliable. For 
instance, all that have to do with moving objects (e.g. velocity != 
0). but the initial object update can't be lost. Any object update 
lost of the login burst is a ghost prim.

Melanie


Justin Clark-Casey wrote:
> Hmm, I then did the obvious thing and compared it (unscientifically) with a couple of sessions on the Linden Lab grid. 
> There, reliable packets appear to compromise approximately 40% of the transfer.
> 
> 
> -------- Original Message --------
> Subject: Does OpenSim need to leave so many packets marked as reliable?
> Date: Thu, 02 Oct 2008 19:32:57 +0100
> From: Justin Clark-Casey <jjustincc at googlemail.com>
> To: opensim-dev at lists.berlios.de
> 
> Hi there,
> 
> A vast number of the packets that we send out from OpenSim (usually >95% according to the statistics printed to the
> Linden viewer log on shutdown) are marked as reliable.  This requires that the viewer respond with an ack, and it just
> doesn't appear that this is done very well when a large number of reliables are sent.  A lot of acks never come and we
> often appear to end up resending thousands (or in the worst case tens of thousands) of packets.
> 
> In a private experiment I've set Header.Reliable = false for the LayerDataPacket and ObjectUpdatePacket (which appear to
> be the greatest sent by count, and which are currently reliable by default in libOMV).  Naturally, this cuts down the
> vast number of resends (and possibly some of the packet_out_of_order messages that come out on the console log) without
> any apparant ill effects.  However, my testing has been pretty limited so I'm minded to wait until Monday before making
> any trunk changes, since then I can get a better load test with multiple avatars (this doesn't stop anybody else testing
> of course :-)
> 
> Any opinions on this?  Is there a good reason for these packets to remain reliable (when resends are probably rare
> anyway)?  libOMV appears to mark every packet as reliable by default...  and then OpenSim removes this from a couple of
> them but not from others.
>