[MUD-Dev] Multi-threaded mud server.

[Jon A. Lambert]

On 16 May 99,, Caliban Tiresias Darklock wrote:
> On 08:42 PM 5/16/99 +0000, I personally witnessed Ross Nicoll jumping up to
> say:
> >
> >The MUD creates as many threads as processors, and then allocates players
> >and computer characters in such a way that load on each processor should
> >be roughly equal. This should keep context switching to a minimum.
> 
> Maybe I don't understand context switching -- my understanding of threads
> is minimal -- but this sounds fallacious. As I understand it, context
> switching is when one thread gives way to another thread, which means its
> state (context) needs to be saved and the other's has to be restored
> (switching). 
>

Yes, but I can't for the life of me figure out why it's so damn important 
to avoid. ;)

Here's a common example:
 
There exists a 400 mhz Pentium II single-processor with 64 Mb of memory 
running Redhat Linux.  Running on the server is ftpd, httpd, telnetd,
smptd, dns, a stock Diku mud server, a DGD LP mud server, and a ColdMUD 
server.  The server is probably underloaded.   

Is there context switching going on here?  YES! Loads and loads of the 
"expensive" process-level context switching.  

<rant>
Now suppose I wish to redesign and multi-thread that Diku mud server.  
Why would I WORRY about the overhead of "cheaper" thread-level context 
switching?
Why should I CARE at the application-level how many processors are 
present on the friggin box!?!@#!??
</rant>


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