[vworld-tech] Maximum Latency?

Jim Purbrick Jpurbrick at climax.co.uk
Fri Feb 20 02:03:49 PST 2004

> Bruce Mitchener 
> But, which latency are you talking about?  Latency is an end-to-end 
> problem and can happen at any point along the way:

The combined latency.

> Some of these you can control, some you can't. Some you can 
> detect, some you can't.  Some will impact everyone, others won't. :)

We can measure the min, max and average latencies we can control and make
sure our game works with them, but there will be network and client latency
on top of that, which we can't control. My question was primarily what to do
about high total latencies and what the client and network latencies we
should have to deal with might be.
> I do think that this is a good reason for having as much per-task 
> accountability as possible.

This is interesting. Is a task your unit of work, which you can start, stop
and schedule? I'm currently thinking about adding support to measure
end-to-end latency in Warhammer, it will measure latency induced by each
processing step and the information will be transmitted with the messages so
will include latency induced by the client, network and servers. It's quite
a lot of work, but it seems that you're saying it's worth it.
> In some current server work, I'm working on making every task 
> transactional (both its in-memory side effects as well as disk and 
> network I/O).  This will give us the ability to have our 
> scheduler and 
> transaction monitor systems report detailed statistics on any 
> given task:
>     * Time to execute
>     * Amount of disk I/O
>     * Amount of network I/O
>     * Number of objects/attributes modified
>     * Possibly number of objects/attributes read
>     * Whatever else we can get

I've got network I/O and as I say I'm looking at latency. Your system sounds
quite neat. Have you got any architectural documents on it?


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